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  99. <li><a class="reference internal" href="#event-loop-methods">Event Loop Methods</a><ul>

  100. <li><a class="reference internal" href="#running-and-stopping-the-loop">Running and stopping the loop</a></li>

  101. <li><a class="reference internal" href="#scheduling-callbacks">Scheduling callbacks</a></li>

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  126. <li><a class="reference internal" href="#set-signal-handlers-for-sigint-and-sigterm">Set signal handlers for SIGINT and SIGTERM</a></li>

  127. </ul>

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  222.   <section id="event-loop">

  223. <span id="asyncio-event-loop"></span><h1>Event Loop<a class="headerlink" href="#event-loop" title="Link to this heading">¶</a></h1>

  224. <p><strong>Source code:</strong> <a class="reference external" href="https://github.com/python/cpython/tree/3.12/Lib/asyncio/events.py">Lib/asyncio/events.py</a>,

  225. <a class="reference external" href="https://github.com/python/cpython/tree/3.12/Lib/asyncio/base_events.py">Lib/asyncio/base_events.py</a></p>

  226. <hr class="docutils" />

  227. <p class="rubric">Preface</p>

  228. <p>The event loop is the core of every asyncio application.

  229. Event loops run asynchronous tasks and callbacks, perform network

  230. IO operations, and run subprocesses.</p>

  231. <p>Application developers should typically use the high-level asyncio functions,

  232. such as <a class="reference internal" href="asyncio-runner.html#asyncio.run" title="asyncio.run"><code class="xref py py-func docutils literal notranslate"><span class="pre">asyncio.run()</span></code></a>, and should rarely need to reference the loop

  233. object or call its methods.  This section is intended mostly for authors

  234. of lower-level code, libraries, and frameworks, who need finer control over

  235. the event loop behavior.</p>

  236. <p class="rubric">Obtaining the Event Loop</p>

  237. <p>The following low-level functions can be used to get, set, or create

  238. an event loop:</p>

  239. <dl class="py function">

  240. <dt class="sig sig-object py" id="asyncio.get_running_loop">

  241. <span class="sig-prename descclassname"><span class="pre">asyncio.</span></span><span class="sig-name descname"><span class="pre">get_running_loop</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.get_running_loop" title="Link to this definition">¶</a></dt>

  242. <dd><p>Return the running event loop in the current OS thread.</p>

  243. <p>Raise a <a class="reference internal" href="exceptions.html#RuntimeError" title="RuntimeError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">RuntimeError</span></code></a> if there is no running event loop.</p>

  244. <p>This function can only be called from a coroutine or a callback.</p>

  245. <div class="versionadded">

  246. <p><span class="versionmodified added">New in version 3.7.</span></p>

  247. </div>

  248. </dd></dl>

  249. 

  250. <dl class="py function">

  251. <dt class="sig sig-object py" id="asyncio.get_event_loop">

  252. <span class="sig-prename descclassname"><span class="pre">asyncio.</span></span><span class="sig-name descname"><span class="pre">get_event_loop</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.get_event_loop" title="Link to this definition">¶</a></dt>

  253. <dd><p>Get the current event loop.</p>

  254. <p>When called from a coroutine or a callback (e.g. scheduled with

  255. call_soon or similar API), this function will always return the

  256. running event loop.</p>

  257. <p>If there is no running event loop set, the function will return

  258. the result of the <code class="docutils literal notranslate"><span class="pre">get_event_loop_policy().get_event_loop()</span></code> call.</p>

  259. <p>Because this function has rather complex behavior (especially

  260. when custom event loop policies are in use), using the

  261. <a class="reference internal" href="#asyncio.get_running_loop" title="asyncio.get_running_loop"><code class="xref py py-func docutils literal notranslate"><span class="pre">get_running_loop()</span></code></a> function is preferred to <a class="reference internal" href="#asyncio.get_event_loop" title="asyncio.get_event_loop"><code class="xref py py-func docutils literal notranslate"><span class="pre">get_event_loop()</span></code></a>

  262. in coroutines and callbacks.</p>

  263. <p>As noted above, consider using the higher-level <a class="reference internal" href="asyncio-runner.html#asyncio.run" title="asyncio.run"><code class="xref py py-func docutils literal notranslate"><span class="pre">asyncio.run()</span></code></a> function,

  264. instead of using these lower level functions to manually create and close an

  265. event loop.</p>

  266. <div class="deprecated">

  267. <p><span class="versionmodified deprecated">Deprecated since version 3.12: </span>Deprecation warning is emitted if there is no current event loop.

  268. In some future Python release this will become an error.</p>

  269. </div>

  270. </dd></dl>

  271. 

  272. <dl class="py function">

  273. <dt class="sig sig-object py" id="asyncio.set_event_loop">

  274. <span class="sig-prename descclassname"><span class="pre">asyncio.</span></span><span class="sig-name descname"><span class="pre">set_event_loop</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">loop</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.set_event_loop" title="Link to this definition">¶</a></dt>

  275. <dd><p>Set <em>loop</em> as the current event loop for the current OS thread.</p>

  276. </dd></dl>

  277. 

  278. <dl class="py function">

  279. <dt class="sig sig-object py" id="asyncio.new_event_loop">

  280. <span class="sig-prename descclassname"><span class="pre">asyncio.</span></span><span class="sig-name descname"><span class="pre">new_event_loop</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.new_event_loop" title="Link to this definition">¶</a></dt>

  281. <dd><p>Create and return a new event loop object.</p>

  282. </dd></dl>

  283. 

  284. <p>Note that the behaviour of <a class="reference internal" href="#asyncio.get_event_loop" title="asyncio.get_event_loop"><code class="xref py py-func docutils literal notranslate"><span class="pre">get_event_loop()</span></code></a>, <a class="reference internal" href="#asyncio.set_event_loop" title="asyncio.set_event_loop"><code class="xref py py-func docutils literal notranslate"><span class="pre">set_event_loop()</span></code></a>,

  285. and <a class="reference internal" href="#asyncio.new_event_loop" title="asyncio.new_event_loop"><code class="xref py py-func docutils literal notranslate"><span class="pre">new_event_loop()</span></code></a> functions can be altered by

  286. <a class="reference internal" href="asyncio-policy.html#asyncio-policies"><span class="std std-ref">setting a custom event loop policy</span></a>.</p>

  287. <p class="rubric">Contents</p>

  288. <p>This documentation page contains the following sections:</p>

  289. <ul class="simple">

  290. <li><p>The <a class="reference internal" href="#event-loop-methods">Event Loop Methods</a> section is the reference documentation of

  291. the event loop APIs;</p></li>

  292. <li><p>The <a class="reference internal" href="#callback-handles">Callback Handles</a> section documents the <a class="reference internal" href="#asyncio.Handle" title="asyncio.Handle"><code class="xref py py-class docutils literal notranslate"><span class="pre">Handle</span></code></a> and

  293. <a class="reference internal" href="#asyncio.TimerHandle" title="asyncio.TimerHandle"><code class="xref py py-class docutils literal notranslate"><span class="pre">TimerHandle</span></code></a> instances which are returned from scheduling

  294. methods such as <a class="reference internal" href="#asyncio.loop.call_soon" title="asyncio.loop.call_soon"><code class="xref py py-meth docutils literal notranslate"><span class="pre">loop.call_soon()</span></code></a> and <a class="reference internal" href="#asyncio.loop.call_later" title="asyncio.loop.call_later"><code class="xref py py-meth docutils literal notranslate"><span class="pre">loop.call_later()</span></code></a>;</p></li>

  295. <li><p>The <a class="reference internal" href="#server-objects">Server Objects</a> section documents types returned from

  296. event loop methods like <a class="reference internal" href="#asyncio.loop.create_server" title="asyncio.loop.create_server"><code class="xref py py-meth docutils literal notranslate"><span class="pre">loop.create_server()</span></code></a>;</p></li>

  297. <li><p>The <a class="reference internal" href="#event-loop-implementations">Event Loop Implementations</a> section documents the

  298. <a class="reference internal" href="#asyncio.SelectorEventLoop" title="asyncio.SelectorEventLoop"><code class="xref py py-class docutils literal notranslate"><span class="pre">SelectorEventLoop</span></code></a> and <a class="reference internal" href="#asyncio.ProactorEventLoop" title="asyncio.ProactorEventLoop"><code class="xref py py-class docutils literal notranslate"><span class="pre">ProactorEventLoop</span></code></a> classes;</p></li>

  299. <li><p>The <a class="reference internal" href="#examples">Examples</a> section showcases how to work with some event

  300. loop APIs.</p></li>

  301. </ul>

  302. <section id="event-loop-methods">

  303. <span id="asyncio-event-loop-methods"></span><h2>Event Loop Methods<a class="headerlink" href="#event-loop-methods" title="Link to this heading">¶</a></h2>

  304. <p>Event loops have <strong>low-level</strong> APIs for the following:</p>

  305. <nav class="contents local" id="contents">

  306. <ul class="simple">

  307. <li><p><a class="reference internal" href="#running-and-stopping-the-loop" id="id1">Running and stopping the loop</a></p></li>

  308. <li><p><a class="reference internal" href="#scheduling-callbacks" id="id2">Scheduling callbacks</a></p></li>

  309. <li><p><a class="reference internal" href="#scheduling-delayed-callbacks" id="id3">Scheduling delayed callbacks</a></p></li>

  310. <li><p><a class="reference internal" href="#creating-futures-and-tasks" id="id4">Creating Futures and Tasks</a></p></li>

  311. <li><p><a class="reference internal" href="#opening-network-connections" id="id5">Opening network connections</a></p></li>

  312. <li><p><a class="reference internal" href="#creating-network-servers" id="id6">Creating network servers</a></p></li>

  313. <li><p><a class="reference internal" href="#transferring-files" id="id7">Transferring files</a></p></li>

  314. <li><p><a class="reference internal" href="#tls-upgrade" id="id8">TLS Upgrade</a></p></li>

  315. <li><p><a class="reference internal" href="#watching-file-descriptors" id="id9">Watching file descriptors</a></p></li>

  316. <li><p><a class="reference internal" href="#working-with-socket-objects-directly" id="id10">Working with socket objects directly</a></p></li>

  317. <li><p><a class="reference internal" href="#dns" id="id11">DNS</a></p></li>

  318. <li><p><a class="reference internal" href="#working-with-pipes" id="id12">Working with pipes</a></p></li>

  319. <li><p><a class="reference internal" href="#unix-signals" id="id13">Unix signals</a></p></li>

  320. <li><p><a class="reference internal" href="#executing-code-in-thread-or-process-pools" id="id14">Executing code in thread or process pools</a></p></li>

  321. <li><p><a class="reference internal" href="#error-handling-api" id="id15">Error Handling API</a></p></li>

  322. <li><p><a class="reference internal" href="#enabling-debug-mode" id="id16">Enabling debug mode</a></p></li>

  323. <li><p><a class="reference internal" href="#running-subprocesses" id="id17">Running Subprocesses</a></p></li>

  324. </ul>

  325. </nav>

  326. <section id="running-and-stopping-the-loop">

  327. <h3><a class="toc-backref" href="#id1" role="doc-backlink">Running and stopping the loop</a><a class="headerlink" href="#running-and-stopping-the-loop" title="Link to this heading">¶</a></h3>

  328. <dl class="py method">

  329. <dt class="sig sig-object py" id="asyncio.loop.run_until_complete">

  330. <span class="sig-prename descclassname"><span class="pre">loop.</span></span><span class="sig-name descname"><span class="pre">run_until_complete</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">future</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.loop.run_until_complete" title="Link to this definition">¶</a></dt>

  331. <dd><p>Run until the <em>future</em> (an instance of <a class="reference internal" href="asyncio-future.html#asyncio.Future" title="asyncio.Future"><code class="xref py py-class docutils literal notranslate"><span class="pre">Future</span></code></a>) has

  332. completed.</p>

  333. <p>If the argument is a <a class="reference internal" href="asyncio-task.html#coroutine"><span class="std std-ref">coroutine object</span></a> it

  334. is implicitly scheduled to run as a <a class="reference internal" href="asyncio-task.html#asyncio.Task" title="asyncio.Task"><code class="xref py py-class docutils literal notranslate"><span class="pre">asyncio.Task</span></code></a>.</p>

  335. <p>Return the Future’s result or raise its exception.</p>

  336. </dd></dl>

  337. 

  338. <dl class="py method">

  339. <dt class="sig sig-object py" id="asyncio.loop.run_forever">

  340. <span class="sig-prename descclassname"><span class="pre">loop.</span></span><span class="sig-name descname"><span class="pre">run_forever</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.loop.run_forever" title="Link to this definition">¶</a></dt>

  341. <dd><p>Run the event loop until <a class="reference internal" href="#asyncio.loop.stop" title="asyncio.loop.stop"><code class="xref py py-meth docutils literal notranslate"><span class="pre">stop()</span></code></a> is called.</p>

  342. <p>If <a class="reference internal" href="#asyncio.loop.stop" title="asyncio.loop.stop"><code class="xref py py-meth docutils literal notranslate"><span class="pre">stop()</span></code></a> is called before <a class="reference internal" href="#asyncio.loop.run_forever" title="asyncio.loop.run_forever"><code class="xref py py-meth docutils literal notranslate"><span class="pre">run_forever()</span></code></a> is called,

  343. the loop will poll the I/O selector once with a timeout of zero,

  344. run all callbacks scheduled in response to I/O events (and

  345. those that were already scheduled), and then exit.</p>

  346. <p>If <a class="reference internal" href="#asyncio.loop.stop" title="asyncio.loop.stop"><code class="xref py py-meth docutils literal notranslate"><span class="pre">stop()</span></code></a> is called while <a class="reference internal" href="#asyncio.loop.run_forever" title="asyncio.loop.run_forever"><code class="xref py py-meth docutils literal notranslate"><span class="pre">run_forever()</span></code></a> is running,

  347. the loop will run the current batch of callbacks and then exit.

  348. Note that new callbacks scheduled by callbacks will not run in this

  349. case; instead, they will run the next time <a class="reference internal" href="#asyncio.loop.run_forever" title="asyncio.loop.run_forever"><code class="xref py py-meth docutils literal notranslate"><span class="pre">run_forever()</span></code></a> or

  350. <a class="reference internal" href="#asyncio.loop.run_until_complete" title="asyncio.loop.run_until_complete"><code class="xref py py-meth docutils literal notranslate"><span class="pre">run_until_complete()</span></code></a> is called.</p>

  351. </dd></dl>

  352. 

  353. <dl class="py method">

  354. <dt class="sig sig-object py" id="asyncio.loop.stop">

  355. <span class="sig-prename descclassname"><span class="pre">loop.</span></span><span class="sig-name descname"><span class="pre">stop</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.loop.stop" title="Link to this definition">¶</a></dt>

  356. <dd><p>Stop the event loop.</p>

  357. </dd></dl>

  358. 

  359. <dl class="py method">

  360. <dt class="sig sig-object py" id="asyncio.loop.is_running">

  361. <span class="sig-prename descclassname"><span class="pre">loop.</span></span><span class="sig-name descname"><span class="pre">is_running</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.loop.is_running" title="Link to this definition">¶</a></dt>

  362. <dd><p>Return <code class="docutils literal notranslate"><span class="pre">True</span></code> if the event loop is currently running.</p>

  363. </dd></dl>

  364. 

  365. <dl class="py method">

  366. <dt class="sig sig-object py" id="asyncio.loop.is_closed">

  367. <span class="sig-prename descclassname"><span class="pre">loop.</span></span><span class="sig-name descname"><span class="pre">is_closed</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.loop.is_closed" title="Link to this definition">¶</a></dt>

  368. <dd><p>Return <code class="docutils literal notranslate"><span class="pre">True</span></code> if the event loop was closed.</p>

  369. </dd></dl>

  370. 

  371. <dl class="py method">

  372. <dt class="sig sig-object py" id="asyncio.loop.close">

  373. <span class="sig-prename descclassname"><span class="pre">loop.</span></span><span class="sig-name descname"><span class="pre">close</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.loop.close" title="Link to this definition">¶</a></dt>

  374. <dd><p>Close the event loop.</p>

  375. <p>The loop must not be running when this function is called.

  376. Any pending callbacks will be discarded.</p>

  377. <p>This method clears all queues and shuts down the executor, but does

  378. not wait for the executor to finish.</p>

  379. <p>This method is idempotent and irreversible.  No other methods

  380. should be called after the event loop is closed.</p>

  381. </dd></dl>

  382. 

  383. <dl class="py method">

  384. <dt class="sig sig-object py" id="asyncio.loop.shutdown_asyncgens">

  385. <em class="property"><span class="pre">coroutine</span> </em><span class="sig-prename descclassname"><span class="pre">loop.</span></span><span class="sig-name descname"><span class="pre">shutdown_asyncgens</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.loop.shutdown_asyncgens" title="Link to this definition">¶</a></dt>

  386. <dd><p>Schedule all currently open <a class="reference internal" href="../glossary.html#term-asynchronous-generator"><span class="xref std std-term">asynchronous generator</span></a> objects to

  387. close with an <a class="reference internal" href="../reference/expressions.html#agen.aclose" title="agen.aclose"><code class="xref py py-meth docutils literal notranslate"><span class="pre">aclose()</span></code></a> call.  After calling this method,

  388. the event loop will issue a warning if a new asynchronous generator

  389. is iterated. This should be used to reliably finalize all scheduled

  390. asynchronous generators.</p>

  391. <p>Note that there is no need to call this function when

  392. <a class="reference internal" href="asyncio-runner.html#asyncio.run" title="asyncio.run"><code class="xref py py-func docutils literal notranslate"><span class="pre">asyncio.run()</span></code></a> is used.</p>

  393. <p>Example:</p>

  394. <div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="k">try</span><span class="p">:</span>

  395.     <span class="n">loop</span><span class="o">.</span><span class="n">run_forever</span><span class="p">()</span>

  396. <span class="k">finally</span><span class="p">:</span>

  397.     <span class="n">loop</span><span class="o">.</span><span class="n">run_until_complete</span><span class="p">(</span><span class="n">loop</span><span class="o">.</span><span class="n">shutdown_asyncgens</span><span class="p">())</span>

  398.     <span class="n">loop</span><span class="o">.</span><span class="n">close</span><span class="p">()</span>

  399. </pre></div>

  400. </div>

  401. <div class="versionadded">

  402. <p><span class="versionmodified added">New in version 3.6.</span></p>

  403. </div>

  404. </dd></dl>

  405. 

  406. <dl class="py method">

  407. <dt class="sig sig-object py" id="asyncio.loop.shutdown_default_executor">

  408. <em class="property"><span class="pre">coroutine</span> </em><span class="sig-prename descclassname"><span class="pre">loop.</span></span><span class="sig-name descname"><span class="pre">shutdown_default_executor</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">timeout</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.loop.shutdown_default_executor" title="Link to this definition">¶</a></dt>

  409. <dd><p>Schedule the closure of the default executor and wait for it to join all of

  410. the threads in the <a class="reference internal" href="concurrent.futures.html#concurrent.futures.ThreadPoolExecutor" title="concurrent.futures.ThreadPoolExecutor"><code class="xref py py-class docutils literal notranslate"><span class="pre">ThreadPoolExecutor</span></code></a>.

  411. Once this method has been called,

  412. using the default executor with <a class="reference internal" href="#asyncio.loop.run_in_executor" title="asyncio.loop.run_in_executor"><code class="xref py py-meth docutils literal notranslate"><span class="pre">loop.run_in_executor()</span></code></a>

  413. will raise a <a class="reference internal" href="exceptions.html#RuntimeError" title="RuntimeError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">RuntimeError</span></code></a>.</p>

  414. <p>The <em>timeout</em> parameter specifies the amount of time

  415. (in <a class="reference internal" href="functions.html#float" title="float"><code class="xref py py-class docutils literal notranslate"><span class="pre">float</span></code></a> seconds) the executor will be given to finish joining.

  416. With the default, <code class="docutils literal notranslate"><span class="pre">None</span></code>,

  417. the executor is allowed an unlimited amount of time.</p>

  418. <p>If the <em>timeout</em> is reached, a <a class="reference internal" href="exceptions.html#RuntimeWarning" title="RuntimeWarning"><code class="xref py py-exc docutils literal notranslate"><span class="pre">RuntimeWarning</span></code></a> is emitted

  419. and the default executor is terminated

  420. without waiting for its threads to finish joining.</p>

  421. <div class="admonition note">

  422. <p class="admonition-title">Note</p>

  423. <p>Do not call this method when using <a class="reference internal" href="asyncio-runner.html#asyncio.run" title="asyncio.run"><code class="xref py py-func docutils literal notranslate"><span class="pre">asyncio.run()</span></code></a>,

  424. as the latter handles default executor shutdown automatically.</p>

  425. </div>

  426. <div class="versionadded">

  427. <p><span class="versionmodified added">New in version 3.9.</span></p>

  428. </div>

  429. <div class="versionchanged">

  430. <p><span class="versionmodified changed">Changed in version 3.12: </span>Added the <em>timeout</em> parameter.</p>

  431. </div>

  432. </dd></dl>

  433. 

  434. </section>

  435. <section id="scheduling-callbacks">

  436. <h3><a class="toc-backref" href="#id2" role="doc-backlink">Scheduling callbacks</a><a class="headerlink" href="#scheduling-callbacks" title="Link to this heading">¶</a></h3>

  437. <dl class="py method">

  438. <dt class="sig sig-object py" id="asyncio.loop.call_soon">

  439. <span class="sig-prename descclassname"><span class="pre">loop.</span></span><span class="sig-name descname"><span class="pre">call_soon</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">callback</span></span></em>, <em class="sig-param"><span class="o"><span class="pre">*</span></span><span class="n"><span class="pre">args</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">context</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.loop.call_soon" title="Link to this definition">¶</a></dt>

  440. <dd><p>Schedule the <em>callback</em> <a class="reference internal" href="../glossary.html#term-callback"><span class="xref std std-term">callback</span></a> to be called with

  441. <em>args</em> arguments at the next iteration of the event loop.</p>

  442. <p>Return an instance of <a class="reference internal" href="#asyncio.Handle" title="asyncio.Handle"><code class="xref py py-class docutils literal notranslate"><span class="pre">asyncio.Handle</span></code></a>,

  443. which can be used later to cancel the callback.</p>

  444. <p>Callbacks are called in the order in which they are registered.

  445. Each callback will be called exactly once.</p>

  446. <p>The optional keyword-only <em>context</em> argument specifies a

  447. custom <a class="reference internal" href="contextvars.html#contextvars.Context" title="contextvars.Context"><code class="xref py py-class docutils literal notranslate"><span class="pre">contextvars.Context</span></code></a> for the <em>callback</em> to run in.

  448. Callbacks use the current context when no <em>context</em> is provided.</p>

  449. <p>Unlike <a class="reference internal" href="#asyncio.loop.call_soon_threadsafe" title="asyncio.loop.call_soon_threadsafe"><code class="xref py py-meth docutils literal notranslate"><span class="pre">call_soon_threadsafe()</span></code></a>, this method is not thread-safe.</p>

  450. </dd></dl>

  451. 

  452. <dl class="py method">

  453. <dt class="sig sig-object py" id="asyncio.loop.call_soon_threadsafe">

  454. <span class="sig-prename descclassname"><span class="pre">loop.</span></span><span class="sig-name descname"><span class="pre">call_soon_threadsafe</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">callback</span></span></em>, <em class="sig-param"><span class="o"><span class="pre">*</span></span><span class="n"><span class="pre">args</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">context</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.loop.call_soon_threadsafe" title="Link to this definition">¶</a></dt>

  455. <dd><p>A thread-safe variant of <a class="reference internal" href="#asyncio.loop.call_soon" title="asyncio.loop.call_soon"><code class="xref py py-meth docutils literal notranslate"><span class="pre">call_soon()</span></code></a>. When scheduling callbacks from

  456. another thread, this function <em>must</em> be used, since <a class="reference internal" href="#asyncio.loop.call_soon" title="asyncio.loop.call_soon"><code class="xref py py-meth docutils literal notranslate"><span class="pre">call_soon()</span></code></a> is not

  457. thread-safe.</p>

  458. <p>Raises <a class="reference internal" href="exceptions.html#RuntimeError" title="RuntimeError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">RuntimeError</span></code></a> if called on a loop that’s been closed.

  459. This can happen on a secondary thread when the main application is

  460. shutting down.</p>

  461. <p>See the <a class="reference internal" href="asyncio-dev.html#asyncio-multithreading"><span class="std std-ref">concurrency and multithreading</span></a>

  462. section of the documentation.</p>

  463. <div class="versionchanged">

  464. <p><span class="versionmodified changed">Changed in version 3.7: </span>The <em>context</em> keyword-only parameter was added. See <span class="target" id="index-0"></span><a class="pep reference external" href="https://peps.python.org/pep-0567/"><strong>PEP 567</strong></a>

  465. for more details.</p>

  466. </div>

  467. </dd></dl>

  468. 

  469. <div class="admonition note" id="asyncio-pass-keywords">

  470. <p class="admonition-title">Note</p>

  471. <p>Most <a class="reference internal" href="asyncio.html#module-asyncio" title="asyncio: Asynchronous I/O."><code class="xref py py-mod docutils literal notranslate"><span class="pre">asyncio</span></code></a> scheduling functions don’t allow passing

  472. keyword arguments.  To do that, use <a class="reference internal" href="functools.html#functools.partial" title="functools.partial"><code class="xref py py-func docutils literal notranslate"><span class="pre">functools.partial()</span></code></a>:</p>

  473. <div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="c1"># will schedule &quot;print(&quot;Hello&quot;, flush=True)&quot;</span>

  474. <span class="n">loop</span><span class="o">.</span><span class="n">call_soon</span><span class="p">(</span>

  475.     <span class="n">functools</span><span class="o">.</span><span class="n">partial</span><span class="p">(</span><span class="nb">print</span><span class="p">,</span> <span class="s2">&quot;Hello&quot;</span><span class="p">,</span> <span class="n">flush</span><span class="o">=</span><span class="kc">True</span><span class="p">))</span>

  476. </pre></div>

  477. </div>

  478. <p>Using partial objects is usually more convenient than using lambdas,

  479. as asyncio can render partial objects better in debug and error

  480. messages.</p>

  481. </div>

  482. </section>

  483. <section id="scheduling-delayed-callbacks">

  484. <span id="asyncio-delayed-calls"></span><h3><a class="toc-backref" href="#id3" role="doc-backlink">Scheduling delayed callbacks</a><a class="headerlink" href="#scheduling-delayed-callbacks" title="Link to this heading">¶</a></h3>

  485. <p>Event loop provides mechanisms to schedule callback functions

  486. to be called at some point in the future.  Event loop uses monotonic

  487. clocks to track time.</p>

  488. <dl class="py method">

  489. <dt class="sig sig-object py" id="asyncio.loop.call_later">

  490. <span class="sig-prename descclassname"><span class="pre">loop.</span></span><span class="sig-name descname"><span class="pre">call_later</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">delay</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">callback</span></span></em>, <em class="sig-param"><span class="o"><span class="pre">*</span></span><span class="n"><span class="pre">args</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">context</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.loop.call_later" title="Link to this definition">¶</a></dt>

  491. <dd><p>Schedule <em>callback</em> to be called after the given <em>delay</em>

  492. number of seconds (can be either an int or a float).</p>

  493. <p>An instance of <a class="reference internal" href="#asyncio.TimerHandle" title="asyncio.TimerHandle"><code class="xref py py-class docutils literal notranslate"><span class="pre">asyncio.TimerHandle</span></code></a> is returned which can

  494. be used to cancel the callback.</p>

  495. <p><em>callback</em> will be called exactly once.  If two callbacks are

  496. scheduled for exactly the same time, the order in which they

  497. are called is undefined.</p>

  498. <p>The optional positional <em>args</em> will be passed to the callback when

  499. it is called. If you want the callback to be called with keyword

  500. arguments use <a class="reference internal" href="functools.html#functools.partial" title="functools.partial"><code class="xref py py-func docutils literal notranslate"><span class="pre">functools.partial()</span></code></a>.</p>

  501. <p>An optional keyword-only <em>context</em> argument allows specifying a

  502. custom <a class="reference internal" href="contextvars.html#contextvars.Context" title="contextvars.Context"><code class="xref py py-class docutils literal notranslate"><span class="pre">contextvars.Context</span></code></a> for the <em>callback</em> to run in.

  503. The current context is used when no <em>context</em> is provided.</p>

  504. <div class="versionchanged">

  505. <p><span class="versionmodified changed">Changed in version 3.7: </span>The <em>context</em> keyword-only parameter was added. See <span class="target" id="index-1"></span><a class="pep reference external" href="https://peps.python.org/pep-0567/"><strong>PEP 567</strong></a>

  506. for more details.</p>

  507. </div>

  508. <div class="versionchanged">

  509. <p><span class="versionmodified changed">Changed in version 3.8: </span>In Python 3.7 and earlier with the default event loop implementation,

  510. the <em>delay</em> could not exceed one day.

  511. This has been fixed in Python 3.8.</p>

  512. </div>

  513. </dd></dl>

  514. 

  515. <dl class="py method">

  516. <dt class="sig sig-object py" id="asyncio.loop.call_at">

  517. <span class="sig-prename descclassname"><span class="pre">loop.</span></span><span class="sig-name descname"><span class="pre">call_at</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">when</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">callback</span></span></em>, <em class="sig-param"><span class="o"><span class="pre">*</span></span><span class="n"><span class="pre">args</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">context</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.loop.call_at" title="Link to this definition">¶</a></dt>

  518. <dd><p>Schedule <em>callback</em> to be called at the given absolute timestamp

  519. <em>when</em> (an int or a float), using the same time reference as

  520. <a class="reference internal" href="#asyncio.loop.time" title="asyncio.loop.time"><code class="xref py py-meth docutils literal notranslate"><span class="pre">loop.time()</span></code></a>.</p>

  521. <p>This method’s behavior is the same as <a class="reference internal" href="#asyncio.loop.call_later" title="asyncio.loop.call_later"><code class="xref py py-meth docutils literal notranslate"><span class="pre">call_later()</span></code></a>.</p>

  522. <p>An instance of <a class="reference internal" href="#asyncio.TimerHandle" title="asyncio.TimerHandle"><code class="xref py py-class docutils literal notranslate"><span class="pre">asyncio.TimerHandle</span></code></a> is returned which can

  523. be used to cancel the callback.</p>

  524. <div class="versionchanged">

  525. <p><span class="versionmodified changed">Changed in version 3.7: </span>The <em>context</em> keyword-only parameter was added. See <span class="target" id="index-2"></span><a class="pep reference external" href="https://peps.python.org/pep-0567/"><strong>PEP 567</strong></a>

  526. for more details.</p>

  527. </div>

  528. <div class="versionchanged">

  529. <p><span class="versionmodified changed">Changed in version 3.8: </span>In Python 3.7 and earlier with the default event loop implementation,

  530. the difference between <em>when</em> and the current time could not exceed

  531. one day.  This has been fixed in Python 3.8.</p>

  532. </div>

  533. </dd></dl>

  534. 

  535. <dl class="py method">

  536. <dt class="sig sig-object py" id="asyncio.loop.time">

  537. <span class="sig-prename descclassname"><span class="pre">loop.</span></span><span class="sig-name descname"><span class="pre">time</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.loop.time" title="Link to this definition">¶</a></dt>

  538. <dd><p>Return the current time, as a <a class="reference internal" href="functions.html#float" title="float"><code class="xref py py-class docutils literal notranslate"><span class="pre">float</span></code></a> value, according to

  539. the event loop’s internal monotonic clock.</p>

  540. </dd></dl>

  541. 

  542. <div class="admonition note">

  543. <p class="admonition-title">Note</p>

  544. <div class="versionchanged">

  545. <p><span class="versionmodified changed">Changed in version 3.8: </span>In Python 3.7 and earlier timeouts (relative <em>delay</em> or absolute <em>when</em>)

  546. should not exceed one day.  This has been fixed in Python 3.8.</p>

  547. </div>

  548. </div>

  549. <div class="admonition seealso">

  550. <p class="admonition-title">See also</p>

  551. <p>The <a class="reference internal" href="asyncio-task.html#asyncio.sleep" title="asyncio.sleep"><code class="xref py py-func docutils literal notranslate"><span class="pre">asyncio.sleep()</span></code></a> function.</p>

  552. </div>

  553. </section>

  554. <section id="creating-futures-and-tasks">

  555. <h3><a class="toc-backref" href="#id4" role="doc-backlink">Creating Futures and Tasks</a><a class="headerlink" href="#creating-futures-and-tasks" title="Link to this heading">¶</a></h3>

  556. <dl class="py method">

  557. <dt class="sig sig-object py" id="asyncio.loop.create_future">

  558. <span class="sig-prename descclassname"><span class="pre">loop.</span></span><span class="sig-name descname"><span class="pre">create_future</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.loop.create_future" title="Link to this definition">¶</a></dt>

  559. <dd><p>Create an <a class="reference internal" href="asyncio-future.html#asyncio.Future" title="asyncio.Future"><code class="xref py py-class docutils literal notranslate"><span class="pre">asyncio.Future</span></code></a> object attached to the event loop.</p>

  560. <p>This is the preferred way to create Futures in asyncio. This lets

  561. third-party event loops provide alternative implementations of

  562. the Future object (with better performance or instrumentation).</p>

  563. <div class="versionadded">

  564. <p><span class="versionmodified added">New in version 3.5.2.</span></p>

  565. </div>

  566. </dd></dl>

  567. 

  568. <dl class="py method">

  569. <dt class="sig sig-object py" id="asyncio.loop.create_task">

  570. <span class="sig-prename descclassname"><span class="pre">loop.</span></span><span class="sig-name descname"><span class="pre">create_task</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">coro</span></span></em>, <em class="sig-param"><span class="o"><span class="pre">*</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">name</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">context</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.loop.create_task" title="Link to this definition">¶</a></dt>

  571. <dd><p>Schedule the execution of <a class="reference internal" href="asyncio-task.html#coroutine"><span class="std std-ref">coroutine</span></a> <em>coro</em>.

  572. Return a <a class="reference internal" href="asyncio-task.html#asyncio.Task" title="asyncio.Task"><code class="xref py py-class docutils literal notranslate"><span class="pre">Task</span></code></a> object.</p>

  573. <p>Third-party event loops can use their own subclass of <a class="reference internal" href="asyncio-task.html#asyncio.Task" title="asyncio.Task"><code class="xref py py-class docutils literal notranslate"><span class="pre">Task</span></code></a>

  574. for interoperability. In this case, the result type is a subclass

  575. of <a class="reference internal" href="asyncio-task.html#asyncio.Task" title="asyncio.Task"><code class="xref py py-class docutils literal notranslate"><span class="pre">Task</span></code></a>.</p>

  576. <p>If the <em>name</em> argument is provided and not <code class="docutils literal notranslate"><span class="pre">None</span></code>, it is set as

  577. the name of the task using <a class="reference internal" href="asyncio-task.html#asyncio.Task.set_name" title="asyncio.Task.set_name"><code class="xref py py-meth docutils literal notranslate"><span class="pre">Task.set_name()</span></code></a>.</p>

  578. <p>An optional keyword-only <em>context</em> argument allows specifying a

  579. custom <a class="reference internal" href="contextvars.html#contextvars.Context" title="contextvars.Context"><code class="xref py py-class docutils literal notranslate"><span class="pre">contextvars.Context</span></code></a> for the <em>coro</em> to run in.

  580. The current context copy is created when no <em>context</em> is provided.</p>

  581. <div class="versionchanged">

  582. <p><span class="versionmodified changed">Changed in version 3.8: </span>Added the <em>name</em> parameter.</p>

  583. </div>

  584. <div class="versionchanged">

  585. <p><span class="versionmodified changed">Changed in version 3.11: </span>Added the <em>context</em> parameter.</p>

  586. </div>

  587. </dd></dl>

  588. 

  589. <dl class="py method">

  590. <dt class="sig sig-object py" id="asyncio.loop.set_task_factory">

  591. <span class="sig-prename descclassname"><span class="pre">loop.</span></span><span class="sig-name descname"><span class="pre">set_task_factory</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">factory</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.loop.set_task_factory" title="Link to this definition">¶</a></dt>

  592. <dd><p>Set a task factory that will be used by

  593. <a class="reference internal" href="#asyncio.loop.create_task" title="asyncio.loop.create_task"><code class="xref py py-meth docutils literal notranslate"><span class="pre">loop.create_task()</span></code></a>.</p>

  594. <p>If <em>factory</em> is <code class="docutils literal notranslate"><span class="pre">None</span></code> the default task factory will be set.

  595. Otherwise, <em>factory</em> must be a <em>callable</em> with the signature matching

  596. <code class="docutils literal notranslate"><span class="pre">(loop,</span> <span class="pre">coro,</span> <span class="pre">context=None)</span></code>, where <em>loop</em> is a reference to the active

  597. event loop, and <em>coro</em> is a coroutine object.  The callable

  598. must return a <a class="reference internal" href="asyncio-future.html#asyncio.Future" title="asyncio.Future"><code class="xref py py-class docutils literal notranslate"><span class="pre">asyncio.Future</span></code></a>-compatible object.</p>

  599. </dd></dl>

  600. 

  601. <dl class="py method">

  602. <dt class="sig sig-object py" id="asyncio.loop.get_task_factory">

  603. <span class="sig-prename descclassname"><span class="pre">loop.</span></span><span class="sig-name descname"><span class="pre">get_task_factory</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.loop.get_task_factory" title="Link to this definition">¶</a></dt>

  604. <dd><p>Return a task factory or <code class="docutils literal notranslate"><span class="pre">None</span></code> if the default one is in use.</p>

  605. </dd></dl>

  606. 

  607. </section>

  608. <section id="opening-network-connections">

  609. <h3><a class="toc-backref" href="#id5" role="doc-backlink">Opening network connections</a><a class="headerlink" href="#opening-network-connections" title="Link to this heading">¶</a></h3>

  610. <dl class="py method">

  611. <dt class="sig sig-object py" id="asyncio.loop.create_connection">

  612. <em class="property"><span class="pre">coroutine</span> </em><span class="sig-prename descclassname"><span class="pre">loop.</span></span><span class="sig-name descname"><span class="pre">create_connection</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">protocol_factory</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">host</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">port</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em>, <em class="sig-param"><span class="o"><span class="pre">*</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">ssl</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">family</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">0</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">proto</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">0</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">flags</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">0</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">sock</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">local_addr</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">server_hostname</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">ssl_handshake_timeout</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">ssl_shutdown_timeout</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">happy_eyeballs_delay</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">interleave</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">all_errors</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">False</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.loop.create_connection" title="Link to this definition">¶</a></dt>

  613. <dd><p>Open a streaming transport connection to a given

  614. address specified by <em>host</em> and <em>port</em>.</p>

  615. <p>The socket family can be either <a class="reference internal" href="socket.html#socket.AF_INET" title="socket.AF_INET"><code class="xref py py-const docutils literal notranslate"><span class="pre">AF_INET</span></code></a> or

  616. <a class="reference internal" href="socket.html#socket.AF_INET6" title="socket.AF_INET6"><code class="xref py py-const docutils literal notranslate"><span class="pre">AF_INET6</span></code></a> depending on <em>host</em> (or the <em>family</em>

  617. argument, if provided).</p>

  618. <p>The socket type will be <a class="reference internal" href="socket.html#socket.SOCK_STREAM" title="socket.SOCK_STREAM"><code class="xref py py-const docutils literal notranslate"><span class="pre">SOCK_STREAM</span></code></a>.</p>

  619. <p><em>protocol_factory</em> must be a callable returning an

  620. <a class="reference internal" href="asyncio-protocol.html#asyncio-protocol"><span class="std std-ref">asyncio protocol</span></a> implementation.</p>

  621. <p>This method will try to establish the connection in the background.

  622. When successful, it returns a <code class="docutils literal notranslate"><span class="pre">(transport,</span> <span class="pre">protocol)</span></code> pair.</p>

  623. <p>The chronological synopsis of the underlying operation is as follows:</p>

  624. <ol class="arabic simple">

  625. <li><p>The connection is established and a <a class="reference internal" href="asyncio-protocol.html#asyncio-transport"><span class="std std-ref">transport</span></a>

  626. is created for it.</p></li>

  627. <li><p><em>protocol_factory</em> is called without arguments and is expected to

  628. return a <a class="reference internal" href="asyncio-protocol.html#asyncio-protocol"><span class="std std-ref">protocol</span></a> instance.</p></li>

  629. <li><p>The protocol instance is coupled with the transport by calling its

  630. <a class="reference internal" href="asyncio-protocol.html#asyncio.BaseProtocol.connection_made" title="asyncio.BaseProtocol.connection_made"><code class="xref py py-meth docutils literal notranslate"><span class="pre">connection_made()</span></code></a> method.</p></li>

  631. <li><p>A <code class="docutils literal notranslate"><span class="pre">(transport,</span> <span class="pre">protocol)</span></code> tuple is returned on success.</p></li>

  632. </ol>

  633. <p>The created transport is an implementation-dependent bidirectional

  634. stream.</p>

  635. <p>Other arguments:</p>

  636. <ul>

  637. <li><p><em>ssl</em>: if given and not false, a SSL/TLS transport is created

  638. (by default a plain TCP transport is created).  If <em>ssl</em> is

  639. a <a class="reference internal" href="ssl.html#ssl.SSLContext" title="ssl.SSLContext"><code class="xref py py-class docutils literal notranslate"><span class="pre">ssl.SSLContext</span></code></a> object, this context is used to create

  640. the transport; if <em>ssl</em> is <a class="reference internal" href="constants.html#True" title="True"><code class="xref py py-const docutils literal notranslate"><span class="pre">True</span></code></a>, a default context returned

  641. from <a class="reference internal" href="ssl.html#ssl.create_default_context" title="ssl.create_default_context"><code class="xref py py-func docutils literal notranslate"><span class="pre">ssl.create_default_context()</span></code></a> is used.</p>

  642. <div class="admonition seealso">

  643. <p class="admonition-title">See also</p>

  644. <p><a class="reference internal" href="ssl.html#ssl-security"><span class="std std-ref">SSL/TLS security considerations</span></a></p>

  645. </div>

  646. </li>

  647. <li><p><em>server_hostname</em> sets or overrides the hostname that the target

  648. server’s certificate will be matched against.  Should only be passed

  649. if <em>ssl</em> is not <code class="docutils literal notranslate"><span class="pre">None</span></code>.  By default the value of the <em>host</em> argument

  650. is used.  If <em>host</em> is empty, there is no default and you must pass a

  651. value for <em>server_hostname</em>.  If <em>server_hostname</em> is an empty

  652. string, hostname matching is disabled (which is a serious security

  653. risk, allowing for potential man-in-the-middle attacks).</p></li>

  654. <li><p><em>family</em>, <em>proto</em>, <em>flags</em> are the optional address family, protocol

  655. and flags to be passed through to getaddrinfo() for <em>host</em> resolution.

  656. If given, these should all be integers from the corresponding

  657. <a class="reference internal" href="socket.html#module-socket" title="socket: Low-level networking interface."><code class="xref py py-mod docutils literal notranslate"><span class="pre">socket</span></code></a> module constants.</p></li>

  658. <li><p><em>happy_eyeballs_delay</em>, if given, enables Happy Eyeballs for this

  659. connection. It should

  660. be a floating-point number representing the amount of time in seconds

  661. to wait for a connection attempt to complete, before starting the next

  662. attempt in parallel. This is the “Connection Attempt Delay” as defined

  663. in <span class="target" id="index-3"></span><a class="rfc reference external" href="https://datatracker.ietf.org/doc/html/rfc8305.html"><strong>RFC 8305</strong></a>. A sensible default value recommended by the RFC is <code class="docutils literal notranslate"><span class="pre">0.25</span></code>

  664. (250 milliseconds).</p></li>

  665. <li><p><em>interleave</em> controls address reordering when a host name resolves to

  666. multiple IP addresses.

  667. If <code class="docutils literal notranslate"><span class="pre">0</span></code> or unspecified, no reordering is done, and addresses are

  668. tried in the order returned by <a class="reference internal" href="#asyncio.loop.getaddrinfo" title="asyncio.loop.getaddrinfo"><code class="xref py py-meth docutils literal notranslate"><span class="pre">getaddrinfo()</span></code></a>. If a positive integer

  669. is specified, the addresses are interleaved by address family, and the

  670. given integer is interpreted as “First Address Family Count” as defined

  671. in <span class="target" id="index-4"></span><a class="rfc reference external" href="https://datatracker.ietf.org/doc/html/rfc8305.html"><strong>RFC 8305</strong></a>. The default is <code class="docutils literal notranslate"><span class="pre">0</span></code> if <em>happy_eyeballs_delay</em> is not

  672. specified, and <code class="docutils literal notranslate"><span class="pre">1</span></code> if it is.</p></li>

  673. <li><p><em>sock</em>, if given, should be an existing, already connected

  674. <a class="reference internal" href="socket.html#socket.socket" title="socket.socket"><code class="xref py py-class docutils literal notranslate"><span class="pre">socket.socket</span></code></a> object to be used by the transport.

  675. If <em>sock</em> is given, none of <em>host</em>, <em>port</em>, <em>family</em>, <em>proto</em>, <em>flags</em>,

  676. <em>happy_eyeballs_delay</em>, <em>interleave</em>

  677. and <em>local_addr</em> should be specified.</p>

  678. <div class="admonition note">

  679. <p class="admonition-title">Note</p>

  680. <p>The <em>sock</em> argument transfers ownership of the socket to the

  681. transport created. To close the socket, call the transport’s

  682. <a class="reference internal" href="asyncio-protocol.html#asyncio.BaseTransport.close" title="asyncio.BaseTransport.close"><code class="xref py py-meth docutils literal notranslate"><span class="pre">close()</span></code></a> method.</p>

  683. </div>

  684. </li>

  685. <li><p><em>local_addr</em>, if given, is a <code class="docutils literal notranslate"><span class="pre">(local_host,</span> <span class="pre">local_port)</span></code> tuple used

  686. to bind the socket locally.  The <em>local_host</em> and <em>local_port</em>

  687. are looked up using <code class="docutils literal notranslate"><span class="pre">getaddrinfo()</span></code>, similarly to <em>host</em> and <em>port</em>.</p></li>

  688. <li><p><em>ssl_handshake_timeout</em> is (for a TLS connection) the time in seconds

  689. to wait for the TLS handshake to complete before aborting the connection.

  690. <code class="docutils literal notranslate"><span class="pre">60.0</span></code> seconds if <code class="docutils literal notranslate"><span class="pre">None</span></code> (default).</p></li>

  691. <li><p><em>ssl_shutdown_timeout</em> is the time in seconds to wait for the SSL shutdown

  692. to complete before aborting the connection. <code class="docutils literal notranslate"><span class="pre">30.0</span></code> seconds if <code class="docutils literal notranslate"><span class="pre">None</span></code>

  693. (default).</p></li>

  694. <li><p><em>all_errors</em> determines what exceptions are raised when a connection cannot

  695. be created. By default, only a single <code class="docutils literal notranslate"><span class="pre">Exception</span></code> is raised: the first

  696. exception if there is only one or all errors have same message, or a single

  697. <code class="docutils literal notranslate"><span class="pre">OSError</span></code> with the error messages combined. When <code class="docutils literal notranslate"><span class="pre">all_errors</span></code> is <code class="docutils literal notranslate"><span class="pre">True</span></code>,

  698. an <code class="docutils literal notranslate"><span class="pre">ExceptionGroup</span></code> will be raised containing all exceptions (even if there

  699. is only one).</p></li>

  700. </ul>

  701. <div class="versionchanged">

  702. <p><span class="versionmodified changed">Changed in version 3.5: </span>Added support for SSL/TLS in <a class="reference internal" href="#asyncio.ProactorEventLoop" title="asyncio.ProactorEventLoop"><code class="xref py py-class docutils literal notranslate"><span class="pre">ProactorEventLoop</span></code></a>.</p>

  703. </div>

  704. <div class="versionchanged">

  705. <p><span class="versionmodified changed">Changed in version 3.6: </span>The socket option <a class="reference internal" href="socket.html#socket-unix-constants"><span class="std std-ref">socket.TCP_NODELAY</span></a> is set by default

  706. for all TCP connections.</p>

  707. </div>

  708. <div class="versionchanged">

  709. <p><span class="versionmodified changed">Changed in version 3.7: </span>Added the <em>ssl_handshake_timeout</em> parameter.</p>

  710. </div>

  711. <div class="versionchanged">

  712. <p><span class="versionmodified changed">Changed in version 3.8: </span>Added the <em>happy_eyeballs_delay</em> and <em>interleave</em> parameters.</p>

  713. <p>Happy Eyeballs Algorithm: Success with Dual-Stack Hosts.

  714. When a server’s IPv4 path and protocol are working, but the server’s

  715. IPv6 path and protocol are not working, a dual-stack client

  716. application experiences significant connection delay compared to an

  717. IPv4-only client.  This is undesirable because it causes the

  718. dual-stack client to have a worse user experience.  This document

  719. specifies requirements for algorithms that reduce this user-visible

  720. delay and provides an algorithm.</p>

  721. <p>For more information: <a class="reference external" href="https://datatracker.ietf.org/doc/html/rfc6555">https://datatracker.ietf.org/doc/html/rfc6555</a></p>

  722. </div>

  723. <div class="versionchanged">

  724. <p><span class="versionmodified changed">Changed in version 3.11: </span>Added the <em>ssl_shutdown_timeout</em> parameter.</p>

  725. </div>

  726. <div class="versionchanged">

  727. <p><span class="versionmodified changed">Changed in version 3.12: </span><em>all_errors</em> was added.</p>

  728. </div>

  729. <div class="admonition seealso">

  730. <p class="admonition-title">See also</p>

  731. <p>The <a class="reference internal" href="asyncio-stream.html#asyncio.open_connection" title="asyncio.open_connection"><code class="xref py py-func docutils literal notranslate"><span class="pre">open_connection()</span></code></a> function is a high-level alternative

  732. API.  It returns a pair of (<a class="reference internal" href="asyncio-stream.html#asyncio.StreamReader" title="asyncio.StreamReader"><code class="xref py py-class docutils literal notranslate"><span class="pre">StreamReader</span></code></a>, <a class="reference internal" href="asyncio-stream.html#asyncio.StreamWriter" title="asyncio.StreamWriter"><code class="xref py py-class docutils literal notranslate"><span class="pre">StreamWriter</span></code></a>)

  733. that can be used directly in async/await code.</p>

  734. </div>

  735. </dd></dl>

  736. 

  737. <dl class="py method">

  738. <dt class="sig sig-object py" id="asyncio.loop.create_datagram_endpoint">

  739. <em class="property"><span class="pre">coroutine</span> </em><span class="sig-prename descclassname"><span class="pre">loop.</span></span><span class="sig-name descname"><span class="pre">create_datagram_endpoint</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">protocol_factory</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">local_addr</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">remote_addr</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em>, <em class="sig-param"><span class="o"><span class="pre">*</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">family</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">0</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">proto</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">0</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">flags</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">0</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">reuse_port</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">allow_broadcast</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">sock</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.loop.create_datagram_endpoint" title="Link to this definition">¶</a></dt>

  740. <dd><p>Create a datagram connection.</p>

  741. <p>The socket family can be either <a class="reference internal" href="socket.html#socket.AF_INET" title="socket.AF_INET"><code class="xref py py-const docutils literal notranslate"><span class="pre">AF_INET</span></code></a>,

  742. <a class="reference internal" href="socket.html#socket.AF_INET6" title="socket.AF_INET6"><code class="xref py py-const docutils literal notranslate"><span class="pre">AF_INET6</span></code></a>, or <a class="reference internal" href="socket.html#socket.AF_UNIX" title="socket.AF_UNIX"><code class="xref py py-const docutils literal notranslate"><span class="pre">AF_UNIX</span></code></a>,

  743. depending on <em>host</em> (or the <em>family</em> argument, if provided).</p>

  744. <p>The socket type will be <a class="reference internal" href="socket.html#socket.SOCK_DGRAM" title="socket.SOCK_DGRAM"><code class="xref py py-const docutils literal notranslate"><span class="pre">SOCK_DGRAM</span></code></a>.</p>

  745. <p><em>protocol_factory</em> must be a callable returning a

  746. <a class="reference internal" href="asyncio-protocol.html#asyncio-protocol"><span class="std std-ref">protocol</span></a> implementation.</p>

  747. <p>A tuple of <code class="docutils literal notranslate"><span class="pre">(transport,</span> <span class="pre">protocol)</span></code> is returned on success.</p>

  748. <p>Other arguments:</p>

  749. <ul>

  750. <li><p><em>local_addr</em>, if given, is a <code class="docutils literal notranslate"><span class="pre">(local_host,</span> <span class="pre">local_port)</span></code> tuple used

  751. to bind the socket locally.  The <em>local_host</em> and <em>local_port</em>

  752. are looked up using <a class="reference internal" href="#asyncio.loop.getaddrinfo" title="asyncio.loop.getaddrinfo"><code class="xref py py-meth docutils literal notranslate"><span class="pre">getaddrinfo()</span></code></a>.</p></li>

  753. <li><p><em>remote_addr</em>, if given, is a <code class="docutils literal notranslate"><span class="pre">(remote_host,</span> <span class="pre">remote_port)</span></code> tuple used

  754. to connect the socket to a remote address.  The <em>remote_host</em> and

  755. <em>remote_port</em> are looked up using <a class="reference internal" href="#asyncio.loop.getaddrinfo" title="asyncio.loop.getaddrinfo"><code class="xref py py-meth docutils literal notranslate"><span class="pre">getaddrinfo()</span></code></a>.</p></li>

  756. <li><p><em>family</em>, <em>proto</em>, <em>flags</em> are the optional address family, protocol

  757. and flags to be passed through to <a class="reference internal" href="#asyncio.loop.getaddrinfo" title="asyncio.loop.getaddrinfo"><code class="xref py py-meth docutils literal notranslate"><span class="pre">getaddrinfo()</span></code></a> for <em>host</em>

  758. resolution. If given, these should all be integers from the

  759. corresponding <a class="reference internal" href="socket.html#module-socket" title="socket: Low-level networking interface."><code class="xref py py-mod docutils literal notranslate"><span class="pre">socket</span></code></a> module constants.</p></li>

  760. <li><p><em>reuse_port</em> tells the kernel to allow this endpoint to be bound to the

  761. same port as other existing endpoints are bound to, so long as they all

  762. set this flag when being created. This option is not supported on Windows

  763. and some Unixes. If the <a class="reference internal" href="socket.html#socket-unix-constants"><span class="std std-ref">socket.SO_REUSEPORT</span></a> constant is not

  764. defined then this capability is unsupported.</p></li>

  765. <li><p><em>allow_broadcast</em> tells the kernel to allow this endpoint to send

  766. messages to the broadcast address.</p></li>

  767. <li><p><em>sock</em> can optionally be specified in order to use a preexisting,

  768. already connected, <a class="reference internal" href="socket.html#socket.socket" title="socket.socket"><code class="xref py py-class docutils literal notranslate"><span class="pre">socket.socket</span></code></a> object to be used by the

  769. transport. If specified, <em>local_addr</em> and <em>remote_addr</em> should be omitted

  770. (must be <a class="reference internal" href="constants.html#None" title="None"><code class="xref py py-const docutils literal notranslate"><span class="pre">None</span></code></a>).</p>

  771. <div class="admonition note">

  772. <p class="admonition-title">Note</p>

  773. <p>The <em>sock</em> argument transfers ownership of the socket to the

  774. transport created. To close the socket, call the transport’s

  775. <a class="reference internal" href="asyncio-protocol.html#asyncio.BaseTransport.close" title="asyncio.BaseTransport.close"><code class="xref py py-meth docutils literal notranslate"><span class="pre">close()</span></code></a> method.</p>

  776. </div>

  777. </li>

  778. </ul>

  779. <p>See <a class="reference internal" href="asyncio-protocol.html#asyncio-udp-echo-client-protocol"><span class="std std-ref">UDP echo client protocol</span></a> and

  780. <a class="reference internal" href="asyncio-protocol.html#asyncio-udp-echo-server-protocol"><span class="std std-ref">UDP echo server protocol</span></a> examples.</p>

  781. <div class="versionchanged">

  782. <p><span class="versionmodified changed">Changed in version 3.4.4: </span>The <em>family</em>, <em>proto</em>, <em>flags</em>, <em>reuse_address</em>, <em>reuse_port</em>,

  783. <em>allow_broadcast</em>, and <em>sock</em> parameters were added.</p>

  784. </div>

  785. <div class="versionchanged">

  786. <p><span class="versionmodified changed">Changed in version 3.8: </span>Added support for Windows.</p>

  787. </div>

  788. <div class="versionchanged">

  789. <p><span class="versionmodified changed">Changed in version 3.8.1: </span>The <em>reuse_address</em> parameter is no longer supported, as using

  790. <a class="reference internal" href="socket.html#socket-unix-constants"><span class="std std-ref">socket.SO_REUSEADDR</span></a>

  791. poses a significant security concern for

  792. UDP. Explicitly passing <code class="docutils literal notranslate"><span class="pre">reuse_address=True</span></code> will raise an exception.</p>

  793. <p>When multiple processes with differing UIDs assign sockets to an

  794. identical UDP socket address with <code class="docutils literal notranslate"><span class="pre">SO_REUSEADDR</span></code>, incoming packets can

  795. become randomly distributed among the sockets.</p>

  796. <p>For supported platforms, <em>reuse_port</em> can be used as a replacement for

  797. similar functionality. With <em>reuse_port</em>,

  798. <a class="reference internal" href="socket.html#socket-unix-constants"><span class="std std-ref">socket.SO_REUSEPORT</span></a>

  799. is used instead, which specifically

  800. prevents processes with differing UIDs from assigning sockets to the same

  801. socket address.</p>

  802. </div>

  803. <div class="versionchanged">

  804. <p><span class="versionmodified changed">Changed in version 3.11: </span>The <em>reuse_address</em> parameter, disabled since Python 3.8.1,

  805. 3.7.6 and 3.6.10, has been entirely removed.</p>

  806. </div>

  807. </dd></dl>

  808. 

  809. <dl class="py method">

  810. <dt class="sig sig-object py" id="asyncio.loop.create_unix_connection">

  811. <em class="property"><span class="pre">coroutine</span> </em><span class="sig-prename descclassname"><span class="pre">loop.</span></span><span class="sig-name descname"><span class="pre">create_unix_connection</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">protocol_factory</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">path</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em>, <em class="sig-param"><span class="o"><span class="pre">*</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">ssl</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">sock</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">server_hostname</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">ssl_handshake_timeout</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">ssl_shutdown_timeout</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.loop.create_unix_connection" title="Link to this definition">¶</a></dt>

  812. <dd><p>Create a Unix connection.</p>

  813. <p>The socket family will be <a class="reference internal" href="socket.html#socket.AF_UNIX" title="socket.AF_UNIX"><code class="xref py py-const docutils literal notranslate"><span class="pre">AF_UNIX</span></code></a>; socket

  814. type will be <a class="reference internal" href="socket.html#socket.SOCK_STREAM" title="socket.SOCK_STREAM"><code class="xref py py-const docutils literal notranslate"><span class="pre">SOCK_STREAM</span></code></a>.</p>

  815. <p>A tuple of <code class="docutils literal notranslate"><span class="pre">(transport,</span> <span class="pre">protocol)</span></code> is returned on success.</p>

  816. <p><em>path</em> is the name of a Unix domain socket and is required,

  817. unless a <em>sock</em> parameter is specified.  Abstract Unix sockets,

  818. <a class="reference internal" href="stdtypes.html#str" title="str"><code class="xref py py-class docutils literal notranslate"><span class="pre">str</span></code></a>, <a class="reference internal" href="stdtypes.html#bytes" title="bytes"><code class="xref py py-class docutils literal notranslate"><span class="pre">bytes</span></code></a>, and <a class="reference internal" href="pathlib.html#pathlib.Path" title="pathlib.Path"><code class="xref py py-class docutils literal notranslate"><span class="pre">Path</span></code></a> paths are

  819. supported.</p>

  820. <p>See the documentation of the <a class="reference internal" href="#asyncio.loop.create_connection" title="asyncio.loop.create_connection"><code class="xref py py-meth docutils literal notranslate"><span class="pre">loop.create_connection()</span></code></a> method

  821. for information about arguments to this method.</p>

  822. <div class="availability docutils container">

  823. <p><a class="reference internal" href="intro.html#availability"><span class="std std-ref">Availability</span></a>: Unix.</p>

  824. </div>

  825. <div class="versionchanged">

  826. <p><span class="versionmodified changed">Changed in version 3.7: </span>Added the <em>ssl_handshake_timeout</em> parameter.

  827. The <em>path</em> parameter can now be a <a class="reference internal" href="../glossary.html#term-path-like-object"><span class="xref std std-term">path-like object</span></a>.</p>

  828. </div>

  829. <div class="versionchanged">

  830. <p><span class="versionmodified changed">Changed in version 3.11: </span>Added the <em>ssl_shutdown_timeout</em> parameter.</p>

  831. </div>

  832. </dd></dl>

  833. 

  834. </section>

  835. <section id="creating-network-servers">

  836. <h3><a class="toc-backref" href="#id6" role="doc-backlink">Creating network servers</a><a class="headerlink" href="#creating-network-servers" title="Link to this heading">¶</a></h3>

  837. <dl class="py method" id="loop-create-server">

  838. <dt class="sig sig-object py" id="asyncio.loop.create_server">

  839. <em class="property"><span class="pre">coroutine</span> </em><span class="sig-prename descclassname"><span class="pre">loop.</span></span><span class="sig-name descname"><span class="pre">create_server</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">protocol_factory</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">host</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">port</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em>, <em class="sig-param"><span class="o"><span class="pre">*</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">family</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">socket.AF_UNSPEC</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">flags</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">socket.AI_PASSIVE</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">sock</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">backlog</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">100</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">ssl</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">reuse_address</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">reuse_port</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">ssl_handshake_timeout</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">ssl_shutdown_timeout</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">start_serving</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">True</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.loop.create_server" title="Link to this definition">¶</a></dt>

  840. <dd><p>Create a TCP server (socket type <a class="reference internal" href="socket.html#socket.SOCK_STREAM" title="socket.SOCK_STREAM"><code class="xref py py-const docutils literal notranslate"><span class="pre">SOCK_STREAM</span></code></a>) listening

  841. on <em>port</em> of the <em>host</em> address.</p>

  842. <p>Returns a <a class="reference internal" href="#asyncio.Server" title="asyncio.Server"><code class="xref py py-class docutils literal notranslate"><span class="pre">Server</span></code></a> object.</p>

  843. <p>Arguments:</p>

  844. <ul>

  845. <li><p><em>protocol_factory</em> must be a callable returning a

  846. <a class="reference internal" href="asyncio-protocol.html#asyncio-protocol"><span class="std std-ref">protocol</span></a> implementation.</p></li>

  847. <li><p>The <em>host</em> parameter can be set to several types which determine where

  848. the server would be listening:</p>

  849. <ul class="simple">

  850. <li><p>If <em>host</em> is a string, the TCP server is bound to a single network

  851. interface specified by <em>host</em>.</p></li>

  852. <li><p>If <em>host</em> is a sequence of strings, the TCP server is bound to all

  853. network interfaces specified by the sequence.</p></li>

  854. <li><p>If <em>host</em> is an empty string or <code class="docutils literal notranslate"><span class="pre">None</span></code>, all interfaces are

  855. assumed and a list of multiple sockets will be returned (most likely

  856. one for IPv4 and another one for IPv6).</p></li>

  857. </ul>

  858. </li>

  859. <li><p>The <em>port</em> parameter can be set to specify which port the server should

  860. listen on. If <code class="docutils literal notranslate"><span class="pre">0</span></code> or <code class="docutils literal notranslate"><span class="pre">None</span></code> (the default), a random unused port will

  861. be selected (note that if <em>host</em> resolves to multiple network interfaces,

  862. a different random port will be selected for each interface).</p></li>

  863. <li><p><em>family</em> can be set to either <a class="reference internal" href="socket.html#socket.AF_INET" title="socket.AF_INET"><code class="xref py py-const docutils literal notranslate"><span class="pre">socket.AF_INET</span></code></a> or

  864. <a class="reference internal" href="socket.html#socket.AF_INET6" title="socket.AF_INET6"><code class="xref py py-const docutils literal notranslate"><span class="pre">AF_INET6</span></code></a> to force the socket to use IPv4 or IPv6.

  865. If not set, the <em>family</em> will be determined from host name

  866. (defaults to <a class="reference internal" href="socket.html#socket.AF_UNSPEC" title="socket.AF_UNSPEC"><code class="xref py py-const docutils literal notranslate"><span class="pre">AF_UNSPEC</span></code></a>).</p></li>

  867. <li><p><em>flags</em> is a bitmask for <a class="reference internal" href="#asyncio.loop.getaddrinfo" title="asyncio.loop.getaddrinfo"><code class="xref py py-meth docutils literal notranslate"><span class="pre">getaddrinfo()</span></code></a>.</p></li>

  868. <li><p><em>sock</em> can optionally be specified in order to use a preexisting

  869. socket object. If specified, <em>host</em> and <em>port</em> must not be specified.</p>

  870. <div class="admonition note">

  871. <p class="admonition-title">Note</p>

  872. <p>The <em>sock</em> argument transfers ownership of the socket to the

  873. server created. To close the socket, call the server’s

  874. <a class="reference internal" href="#asyncio.Server.close" title="asyncio.Server.close"><code class="xref py py-meth docutils literal notranslate"><span class="pre">close()</span></code></a> method.</p>

  875. </div>

  876. </li>

  877. <li><p><em>backlog</em> is the maximum number of queued connections passed to

  878. <a class="reference internal" href="socket.html#socket.socket.listen" title="socket.socket.listen"><code class="xref py py-meth docutils literal notranslate"><span class="pre">listen()</span></code></a> (defaults to 100).</p></li>

  879. <li><p><em>ssl</em> can be set to an <a class="reference internal" href="ssl.html#ssl.SSLContext" title="ssl.SSLContext"><code class="xref py py-class docutils literal notranslate"><span class="pre">SSLContext</span></code></a> instance to enable

  880. TLS over the accepted connections.</p></li>

  881. <li><p><em>reuse_address</em> tells the kernel to reuse a local socket in

  882. <code class="docutils literal notranslate"><span class="pre">TIME_WAIT</span></code> state, without waiting for its natural timeout to

  883. expire. If not specified will automatically be set to <code class="docutils literal notranslate"><span class="pre">True</span></code> on

  884. Unix.</p></li>

  885. <li><p><em>reuse_port</em> tells the kernel to allow this endpoint to be bound to the

  886. same port as other existing endpoints are bound to, so long as they all

  887. set this flag when being created. This option is not supported on

  888. Windows.</p></li>

  889. <li><p><em>ssl_handshake_timeout</em> is (for a TLS server) the time in seconds to wait

  890. for the TLS handshake to complete before aborting the connection.

  891. <code class="docutils literal notranslate"><span class="pre">60.0</span></code> seconds if <code class="docutils literal notranslate"><span class="pre">None</span></code> (default).</p></li>

  892. <li><p><em>ssl_shutdown_timeout</em> is the time in seconds to wait for the SSL shutdown

  893. to complete before aborting the connection. <code class="docutils literal notranslate"><span class="pre">30.0</span></code> seconds if <code class="docutils literal notranslate"><span class="pre">None</span></code>

  894. (default).</p></li>

  895. <li><p><em>start_serving</em> set to <code class="docutils literal notranslate"><span class="pre">True</span></code> (the default) causes the created server

  896. to start accepting connections immediately.  When set to <code class="docutils literal notranslate"><span class="pre">False</span></code>,

  897. the user should await on <a class="reference internal" href="#asyncio.Server.start_serving" title="asyncio.Server.start_serving"><code class="xref py py-meth docutils literal notranslate"><span class="pre">Server.start_serving()</span></code></a> or

  898. <a class="reference internal" href="#asyncio.Server.serve_forever" title="asyncio.Server.serve_forever"><code class="xref py py-meth docutils literal notranslate"><span class="pre">Server.serve_forever()</span></code></a> to make the server to start accepting

  899. connections.</p></li>

  900. </ul>

  901. <div class="versionchanged">

  902. <p><span class="versionmodified changed">Changed in version 3.5: </span>Added support for SSL/TLS in <a class="reference internal" href="#asyncio.ProactorEventLoop" title="asyncio.ProactorEventLoop"><code class="xref py py-class docutils literal notranslate"><span class="pre">ProactorEventLoop</span></code></a>.</p>

  903. </div>

  904. <div class="versionchanged">

  905. <p><span class="versionmodified changed">Changed in version 3.5.1: </span>The <em>host</em> parameter can be a sequence of strings.</p>

  906. </div>

  907. <div class="versionchanged">

  908. <p><span class="versionmodified changed">Changed in version 3.6: </span>Added <em>ssl_handshake_timeout</em> and <em>start_serving</em> parameters.

  909. The socket option <a class="reference internal" href="socket.html#socket-unix-constants"><span class="std std-ref">socket.TCP_NODELAY</span></a> is set by default

  910. for all TCP connections.</p>

  911. </div>

  912. <div class="versionchanged">

  913. <p><span class="versionmodified changed">Changed in version 3.11: </span>Added the <em>ssl_shutdown_timeout</em> parameter.</p>

  914. </div>

  915. <div class="admonition seealso">

  916. <p class="admonition-title">See also</p>

  917. <p>The <a class="reference internal" href="asyncio-stream.html#asyncio.start_server" title="asyncio.start_server"><code class="xref py py-func docutils literal notranslate"><span class="pre">start_server()</span></code></a> function is a higher-level alternative API

  918. that returns a pair of <a class="reference internal" href="asyncio-stream.html#asyncio.StreamReader" title="asyncio.StreamReader"><code class="xref py py-class docutils literal notranslate"><span class="pre">StreamReader</span></code></a> and <a class="reference internal" href="asyncio-stream.html#asyncio.StreamWriter" title="asyncio.StreamWriter"><code class="xref py py-class docutils literal notranslate"><span class="pre">StreamWriter</span></code></a>

  919. that can be used in an async/await code.</p>

  920. </div>

  921. </dd></dl>

  922. 

  923. <dl class="py method">

  924. <dt class="sig sig-object py" id="asyncio.loop.create_unix_server">

  925. <em class="property"><span class="pre">coroutine</span> </em><span class="sig-prename descclassname"><span class="pre">loop.</span></span><span class="sig-name descname"><span class="pre">create_unix_server</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">protocol_factory</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">path</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em>, <em class="sig-param"><span class="o"><span class="pre">*</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">sock</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">backlog</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">100</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">ssl</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">ssl_handshake_timeout</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">ssl_shutdown_timeout</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">start_serving</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">True</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.loop.create_unix_server" title="Link to this definition">¶</a></dt>

  926. <dd><p>Similar to <a class="reference internal" href="#asyncio.loop.create_server" title="asyncio.loop.create_server"><code class="xref py py-meth docutils literal notranslate"><span class="pre">loop.create_server()</span></code></a> but works with the

  927. <a class="reference internal" href="socket.html#socket.AF_UNIX" title="socket.AF_UNIX"><code class="xref py py-const docutils literal notranslate"><span class="pre">AF_UNIX</span></code></a> socket family.</p>

  928. <p><em>path</em> is the name of a Unix domain socket, and is required,

  929. unless a <em>sock</em> argument is provided.  Abstract Unix sockets,

  930. <a class="reference internal" href="stdtypes.html#str" title="str"><code class="xref py py-class docutils literal notranslate"><span class="pre">str</span></code></a>, <a class="reference internal" href="stdtypes.html#bytes" title="bytes"><code class="xref py py-class docutils literal notranslate"><span class="pre">bytes</span></code></a>, and <a class="reference internal" href="pathlib.html#pathlib.Path" title="pathlib.Path"><code class="xref py py-class docutils literal notranslate"><span class="pre">Path</span></code></a> paths

  931. are supported.</p>

  932. <p>See the documentation of the <a class="reference internal" href="#asyncio.loop.create_server" title="asyncio.loop.create_server"><code class="xref py py-meth docutils literal notranslate"><span class="pre">loop.create_server()</span></code></a> method

  933. for information about arguments to this method.</p>

  934. <div class="availability docutils container">

  935. <p><a class="reference internal" href="intro.html#availability"><span class="std std-ref">Availability</span></a>: Unix.</p>

  936. </div>

  937. <div class="versionchanged">

  938. <p><span class="versionmodified changed">Changed in version 3.7: </span>Added the <em>ssl_handshake_timeout</em> and <em>start_serving</em> parameters.

  939. The <em>path</em> parameter can now be a <a class="reference internal" href="pathlib.html#pathlib.Path" title="pathlib.Path"><code class="xref py py-class docutils literal notranslate"><span class="pre">Path</span></code></a> object.</p>

  940. </div>

  941. <div class="versionchanged">

  942. <p><span class="versionmodified changed">Changed in version 3.11: </span>Added the <em>ssl_shutdown_timeout</em> parameter.</p>

  943. </div>

  944. </dd></dl>

  945. 

  946. <dl class="py method">

  947. <dt class="sig sig-object py" id="asyncio.loop.connect_accepted_socket">

  948. <em class="property"><span class="pre">coroutine</span> </em><span class="sig-prename descclassname"><span class="pre">loop.</span></span><span class="sig-name descname"><span class="pre">connect_accepted_socket</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">protocol_factory</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">sock</span></span></em>, <em class="sig-param"><span class="o"><span class="pre">*</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">ssl</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">ssl_handshake_timeout</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">ssl_shutdown_timeout</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.loop.connect_accepted_socket" title="Link to this definition">¶</a></dt>

  949. <dd><p>Wrap an already accepted connection into a transport/protocol pair.</p>

  950. <p>This method can be used by servers that accept connections outside

  951. of asyncio but that use asyncio to handle them.</p>

  952. <p>Parameters:</p>

  953. <ul>

  954. <li><p><em>protocol_factory</em> must be a callable returning a

  955. <a class="reference internal" href="asyncio-protocol.html#asyncio-protocol"><span class="std std-ref">protocol</span></a> implementation.</p></li>

  956. <li><p><em>sock</em> is a preexisting socket object returned from

  957. <a class="reference internal" href="socket.html#socket.socket.accept" title="socket.socket.accept"><code class="xref py py-meth docutils literal notranslate"><span class="pre">socket.accept</span></code></a>.</p>

  958. <div class="admonition note">

  959. <p class="admonition-title">Note</p>

  960. <p>The <em>sock</em> argument transfers ownership of the socket to the

  961. transport created. To close the socket, call the transport’s

  962. <a class="reference internal" href="asyncio-protocol.html#asyncio.BaseTransport.close" title="asyncio.BaseTransport.close"><code class="xref py py-meth docutils literal notranslate"><span class="pre">close()</span></code></a> method.</p>

  963. </div>

  964. </li>

  965. <li><p><em>ssl</em> can be set to an <a class="reference internal" href="ssl.html#ssl.SSLContext" title="ssl.SSLContext"><code class="xref py py-class docutils literal notranslate"><span class="pre">SSLContext</span></code></a> to enable SSL over

  966. the accepted connections.</p></li>

  967. <li><p><em>ssl_handshake_timeout</em> is (for an SSL connection) the time in seconds to

  968. wait for the SSL handshake to complete before aborting the connection.

  969. <code class="docutils literal notranslate"><span class="pre">60.0</span></code> seconds if <code class="docutils literal notranslate"><span class="pre">None</span></code> (default).</p></li>

  970. <li><p><em>ssl_shutdown_timeout</em> is the time in seconds to wait for the SSL shutdown

  971. to complete before aborting the connection. <code class="docutils literal notranslate"><span class="pre">30.0</span></code> seconds if <code class="docutils literal notranslate"><span class="pre">None</span></code>

  972. (default).</p></li>

  973. </ul>

  974. <p>Returns a <code class="docutils literal notranslate"><span class="pre">(transport,</span> <span class="pre">protocol)</span></code> pair.</p>

  975. <div class="versionadded">

  976. <p><span class="versionmodified added">New in version 3.5.3.</span></p>

  977. </div>

  978. <div class="versionchanged">

  979. <p><span class="versionmodified changed">Changed in version 3.7: </span>Added the <em>ssl_handshake_timeout</em> parameter.</p>

  980. </div>

  981. <div class="versionchanged">

  982. <p><span class="versionmodified changed">Changed in version 3.11: </span>Added the <em>ssl_shutdown_timeout</em> parameter.</p>

  983. </div>

  984. </dd></dl>

  985. 

  986. </section>

  987. <section id="transferring-files">

  988. <h3><a class="toc-backref" href="#id7" role="doc-backlink">Transferring files</a><a class="headerlink" href="#transferring-files" title="Link to this heading">¶</a></h3>

  989. <dl class="py method">

  990. <dt class="sig sig-object py" id="asyncio.loop.sendfile">

  991. <em class="property"><span class="pre">coroutine</span> </em><span class="sig-prename descclassname"><span class="pre">loop.</span></span><span class="sig-name descname"><span class="pre">sendfile</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">transport</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">file</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">offset</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">0</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">count</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em>, <em class="sig-param"><span class="o"><span class="pre">*</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">fallback</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">True</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.loop.sendfile" title="Link to this definition">¶</a></dt>

  992. <dd><p>Send a <em>file</em> over a <em>transport</em>.  Return the total number of bytes

  993. sent.</p>

  994. <p>The method uses high-performance <a class="reference internal" href="os.html#os.sendfile" title="os.sendfile"><code class="xref py py-meth docutils literal notranslate"><span class="pre">os.sendfile()</span></code></a> if available.</p>

  995. <p><em>file</em> must be a regular file object opened in binary mode.</p>

  996. <p><em>offset</em> tells from where to start reading the file. If specified,

  997. <em>count</em> is the total number of bytes to transmit as opposed to

  998. sending the file until EOF is reached. File position is always updated,

  999. even when this method raises an error, and

  1000. <a class="reference internal" href="io.html#io.IOBase.tell" title="io.IOBase.tell"><code class="xref py py-meth docutils literal notranslate"><span class="pre">file.tell()</span></code></a> can be used to obtain the actual

  1001. number of bytes sent.</p>

  1002. <p><em>fallback</em> set to <code class="docutils literal notranslate"><span class="pre">True</span></code> makes asyncio to manually read and send

  1003. the file when the platform does not support the sendfile system call

  1004. (e.g. Windows or SSL socket on Unix).</p>

  1005. <p>Raise <a class="reference internal" href="asyncio-exceptions.html#asyncio.SendfileNotAvailableError" title="asyncio.SendfileNotAvailableError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">SendfileNotAvailableError</span></code></a> if the system does not support

  1006. the <em>sendfile</em> syscall and <em>fallback</em> is <code class="docutils literal notranslate"><span class="pre">False</span></code>.</p>

  1007. <div class="versionadded">

  1008. <p><span class="versionmodified added">New in version 3.7.</span></p>

  1009. </div>

  1010. </dd></dl>

  1011. 

  1012. </section>

  1013. <section id="tls-upgrade">

  1014. <h3><a class="toc-backref" href="#id8" role="doc-backlink">TLS Upgrade</a><a class="headerlink" href="#tls-upgrade" title="Link to this heading">¶</a></h3>

  1015. <dl class="py method">

  1016. <dt class="sig sig-object py" id="asyncio.loop.start_tls">

  1017. <em class="property"><span class="pre">coroutine</span> </em><span class="sig-prename descclassname"><span class="pre">loop.</span></span><span class="sig-name descname"><span class="pre">start_tls</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">transport</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">protocol</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">sslcontext</span></span></em>, <em class="sig-param"><span class="o"><span class="pre">*</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">server_side</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">False</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">server_hostname</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">ssl_handshake_timeout</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">ssl_shutdown_timeout</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.loop.start_tls" title="Link to this definition">¶</a></dt>

  1018. <dd><p>Upgrade an existing transport-based connection to TLS.</p>

  1019. <p>Create a TLS coder/decoder instance and insert it between the <em>transport</em>

  1020. and the <em>protocol</em>. The coder/decoder implements both <em>transport</em>-facing

  1021. protocol and <em>protocol</em>-facing transport.</p>

  1022. <p>Return the created two-interface instance. After <em>await</em>, the <em>protocol</em>

  1023. must stop using the original <em>transport</em> and communicate with the returned

  1024. object only because the coder caches <em>protocol</em>-side data and sporadically

  1025. exchanges extra TLS session packets with <em>transport</em>.</p>

  1026. <p>In some situations (e.g. when the passed transport is already closing) this

  1027. may return <code class="docutils literal notranslate"><span class="pre">None</span></code>.</p>

  1028. <p>Parameters:</p>

  1029. <ul class="simple">

  1030. <li><p><em>transport</em> and <em>protocol</em> instances that methods like

  1031. <a class="reference internal" href="#asyncio.loop.create_server" title="asyncio.loop.create_server"><code class="xref py py-meth docutils literal notranslate"><span class="pre">create_server()</span></code></a> and

  1032. <a class="reference internal" href="#asyncio.loop.create_connection" title="asyncio.loop.create_connection"><code class="xref py py-meth docutils literal notranslate"><span class="pre">create_connection()</span></code></a> return.</p></li>

  1033. <li><p><em>sslcontext</em>: a configured instance of <a class="reference internal" href="ssl.html#ssl.SSLContext" title="ssl.SSLContext"><code class="xref py py-class docutils literal notranslate"><span class="pre">SSLContext</span></code></a>.</p></li>

  1034. <li><p><em>server_side</em> pass <code class="docutils literal notranslate"><span class="pre">True</span></code> when a server-side connection is being

  1035. upgraded (like the one created by <a class="reference internal" href="#asyncio.loop.create_server" title="asyncio.loop.create_server"><code class="xref py py-meth docutils literal notranslate"><span class="pre">create_server()</span></code></a>).</p></li>

  1036. <li><p><em>server_hostname</em>: sets or overrides the host name that the target

  1037. server’s certificate will be matched against.</p></li>

  1038. <li><p><em>ssl_handshake_timeout</em> is (for a TLS connection) the time in seconds to

  1039. wait for the TLS handshake to complete before aborting the connection.

  1040. <code class="docutils literal notranslate"><span class="pre">60.0</span></code> seconds if <code class="docutils literal notranslate"><span class="pre">None</span></code> (default).</p></li>

  1041. <li><p><em>ssl_shutdown_timeout</em> is the time in seconds to wait for the SSL shutdown

  1042. to complete before aborting the connection. <code class="docutils literal notranslate"><span class="pre">30.0</span></code> seconds if <code class="docutils literal notranslate"><span class="pre">None</span></code>

  1043. (default).</p></li>

  1044. </ul>

  1045. <div class="versionadded">

  1046. <p><span class="versionmodified added">New in version 3.7.</span></p>

  1047. </div>

  1048. <div class="versionchanged">

  1049. <p><span class="versionmodified changed">Changed in version 3.11: </span>Added the <em>ssl_shutdown_timeout</em> parameter.</p>

  1050. </div>

  1051. </dd></dl>

  1052. 

  1053. </section>

  1054. <section id="watching-file-descriptors">

  1055. <h3><a class="toc-backref" href="#id9" role="doc-backlink">Watching file descriptors</a><a class="headerlink" href="#watching-file-descriptors" title="Link to this heading">¶</a></h3>

  1056. <dl class="py method">

  1057. <dt class="sig sig-object py" id="asyncio.loop.add_reader">

  1058. <span class="sig-prename descclassname"><span class="pre">loop.</span></span><span class="sig-name descname"><span class="pre">add_reader</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">fd</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">callback</span></span></em>, <em class="sig-param"><span class="o"><span class="pre">*</span></span><span class="n"><span class="pre">args</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.loop.add_reader" title="Link to this definition">¶</a></dt>

  1059. <dd><p>Start monitoring the <em>fd</em> file descriptor for read availability and

  1060. invoke <em>callback</em> with the specified arguments once <em>fd</em> is available for

  1061. reading.</p>

  1062. </dd></dl>

  1063. 

  1064. <dl class="py method">

  1065. <dt class="sig sig-object py" id="asyncio.loop.remove_reader">

  1066. <span class="sig-prename descclassname"><span class="pre">loop.</span></span><span class="sig-name descname"><span class="pre">remove_reader</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">fd</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.loop.remove_reader" title="Link to this definition">¶</a></dt>

  1067. <dd><p>Stop monitoring the <em>fd</em> file descriptor for read availability. Returns

  1068. <code class="docutils literal notranslate"><span class="pre">True</span></code> if <em>fd</em> was previously being monitored for reads.</p>

  1069. </dd></dl>

  1070. 

  1071. <dl class="py method">

  1072. <dt class="sig sig-object py" id="asyncio.loop.add_writer">

  1073. <span class="sig-prename descclassname"><span class="pre">loop.</span></span><span class="sig-name descname"><span class="pre">add_writer</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">fd</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">callback</span></span></em>, <em class="sig-param"><span class="o"><span class="pre">*</span></span><span class="n"><span class="pre">args</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.loop.add_writer" title="Link to this definition">¶</a></dt>

  1074. <dd><p>Start monitoring the <em>fd</em> file descriptor for write availability and

  1075. invoke <em>callback</em> with the specified arguments once <em>fd</em> is available for

  1076. writing.</p>

  1077. <p>Use <a class="reference internal" href="functools.html#functools.partial" title="functools.partial"><code class="xref py py-func docutils literal notranslate"><span class="pre">functools.partial()</span></code></a> <a class="reference internal" href="#asyncio-pass-keywords"><span class="std std-ref">to pass keyword arguments</span></a> to <em>callback</em>.</p>

  1078. </dd></dl>

  1079. 

  1080. <dl class="py method">

  1081. <dt class="sig sig-object py" id="asyncio.loop.remove_writer">

  1082. <span class="sig-prename descclassname"><span class="pre">loop.</span></span><span class="sig-name descname"><span class="pre">remove_writer</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">fd</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.loop.remove_writer" title="Link to this definition">¶</a></dt>

  1083. <dd><p>Stop monitoring the <em>fd</em> file descriptor for write availability. Returns

  1084. <code class="docutils literal notranslate"><span class="pre">True</span></code> if <em>fd</em> was previously being monitored for writes.</p>

  1085. </dd></dl>

  1086. 

  1087. <p>See also <a class="reference internal" href="asyncio-platforms.html#asyncio-platform-support"><span class="std std-ref">Platform Support</span></a> section

  1088. for some limitations of these methods.</p>

  1089. </section>

  1090. <section id="working-with-socket-objects-directly">

  1091. <h3><a class="toc-backref" href="#id10" role="doc-backlink">Working with socket objects directly</a><a class="headerlink" href="#working-with-socket-objects-directly" title="Link to this heading">¶</a></h3>

  1092. <p>In general, protocol implementations that use transport-based APIs

  1093. such as <a class="reference internal" href="#asyncio.loop.create_connection" title="asyncio.loop.create_connection"><code class="xref py py-meth docutils literal notranslate"><span class="pre">loop.create_connection()</span></code></a> and <a class="reference internal" href="#asyncio.loop.create_server" title="asyncio.loop.create_server"><code class="xref py py-meth docutils literal notranslate"><span class="pre">loop.create_server()</span></code></a>

  1094. are faster than implementations that work with sockets directly.

  1095. However, there are some use cases when performance is not critical, and

  1096. working with <a class="reference internal" href="socket.html#socket.socket" title="socket.socket"><code class="xref py py-class docutils literal notranslate"><span class="pre">socket</span></code></a> objects directly is more

  1097. convenient.</p>

  1098. <dl class="py method">

  1099. <dt class="sig sig-object py" id="asyncio.loop.sock_recv">

  1100. <em class="property"><span class="pre">coroutine</span> </em><span class="sig-prename descclassname"><span class="pre">loop.</span></span><span class="sig-name descname"><span class="pre">sock_recv</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">sock</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">nbytes</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.loop.sock_recv" title="Link to this definition">¶</a></dt>

  1101. <dd><p>Receive up to <em>nbytes</em> from <em>sock</em>.  Asynchronous version of

  1102. <a class="reference internal" href="socket.html#socket.socket.recv" title="socket.socket.recv"><code class="xref py py-meth docutils literal notranslate"><span class="pre">socket.recv()</span></code></a>.</p>

  1103. <p>Return the received data as a bytes object.</p>

  1104. <p><em>sock</em> must be a non-blocking socket.</p>

  1105. <div class="versionchanged">

  1106. <p><span class="versionmodified changed">Changed in version 3.7: </span>Even though this method was always documented as a coroutine

  1107. method, releases before Python 3.7 returned a <a class="reference internal" href="asyncio-future.html#asyncio.Future" title="asyncio.Future"><code class="xref py py-class docutils literal notranslate"><span class="pre">Future</span></code></a>.

  1108. Since Python 3.7 this is an <code class="docutils literal notranslate"><span class="pre">async</span> <span class="pre">def</span></code> method.</p>

  1109. </div>

  1110. </dd></dl>

  1111. 

  1112. <dl class="py method">

  1113. <dt class="sig sig-object py" id="asyncio.loop.sock_recv_into">

  1114. <em class="property"><span class="pre">coroutine</span> </em><span class="sig-prename descclassname"><span class="pre">loop.</span></span><span class="sig-name descname"><span class="pre">sock_recv_into</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">sock</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">buf</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.loop.sock_recv_into" title="Link to this definition">¶</a></dt>

  1115. <dd><p>Receive data from <em>sock</em> into the <em>buf</em> buffer.  Modeled after the blocking

  1116. <a class="reference internal" href="socket.html#socket.socket.recv_into" title="socket.socket.recv_into"><code class="xref py py-meth docutils literal notranslate"><span class="pre">socket.recv_into()</span></code></a> method.</p>

  1117. <p>Return the number of bytes written to the buffer.</p>

  1118. <p><em>sock</em> must be a non-blocking socket.</p>

  1119. <div class="versionadded">

  1120. <p><span class="versionmodified added">New in version 3.7.</span></p>

  1121. </div>

  1122. </dd></dl>

  1123. 

  1124. <dl class="py method">

  1125. <dt class="sig sig-object py" id="asyncio.loop.sock_recvfrom">

  1126. <em class="property"><span class="pre">coroutine</span> </em><span class="sig-prename descclassname"><span class="pre">loop.</span></span><span class="sig-name descname"><span class="pre">sock_recvfrom</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">sock</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">bufsize</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.loop.sock_recvfrom" title="Link to this definition">¶</a></dt>

  1127. <dd><p>Receive a datagram of up to <em>bufsize</em> from <em>sock</em>.  Asynchronous version of

  1128. <a class="reference internal" href="socket.html#socket.socket.recvfrom" title="socket.socket.recvfrom"><code class="xref py py-meth docutils literal notranslate"><span class="pre">socket.recvfrom()</span></code></a>.</p>

  1129. <p>Return a tuple of (received data, remote address).</p>

  1130. <p><em>sock</em> must be a non-blocking socket.</p>

  1131. <div class="versionadded">

  1132. <p><span class="versionmodified added">New in version 3.11.</span></p>

  1133. </div>

  1134. </dd></dl>

  1135. 

  1136. <dl class="py method">

  1137. <dt class="sig sig-object py" id="asyncio.loop.sock_recvfrom_into">

  1138. <em class="property"><span class="pre">coroutine</span> </em><span class="sig-prename descclassname"><span class="pre">loop.</span></span><span class="sig-name descname"><span class="pre">sock_recvfrom_into</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">sock</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">buf</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">nbytes</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">0</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.loop.sock_recvfrom_into" title="Link to this definition">¶</a></dt>

  1139. <dd><p>Receive a datagram of up to <em>nbytes</em> from <em>sock</em> into <em>buf</em>.

  1140. Asynchronous version of

  1141. <a class="reference internal" href="socket.html#socket.socket.recvfrom_into" title="socket.socket.recvfrom_into"><code class="xref py py-meth docutils literal notranslate"><span class="pre">socket.recvfrom_into()</span></code></a>.</p>

  1142. <p>Return a tuple of (number of bytes received, remote address).</p>

  1143. <p><em>sock</em> must be a non-blocking socket.</p>

  1144. <div class="versionadded">

  1145. <p><span class="versionmodified added">New in version 3.11.</span></p>

  1146. </div>

  1147. </dd></dl>

  1148. 

  1149. <dl class="py method">

  1150. <dt class="sig sig-object py" id="asyncio.loop.sock_sendall">

  1151. <em class="property"><span class="pre">coroutine</span> </em><span class="sig-prename descclassname"><span class="pre">loop.</span></span><span class="sig-name descname"><span class="pre">sock_sendall</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">sock</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">data</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.loop.sock_sendall" title="Link to this definition">¶</a></dt>

  1152. <dd><p>Send <em>data</em> to the <em>sock</em> socket. Asynchronous version of

  1153. <a class="reference internal" href="socket.html#socket.socket.sendall" title="socket.socket.sendall"><code class="xref py py-meth docutils literal notranslate"><span class="pre">socket.sendall()</span></code></a>.</p>

  1154. <p>This method continues to send to the socket until either all data

  1155. in <em>data</em> has been sent or an error occurs.  <code class="docutils literal notranslate"><span class="pre">None</span></code> is returned

  1156. on success.  On error, an exception is raised. Additionally, there is no way

  1157. to determine how much data, if any, was successfully processed by the

  1158. receiving end of the connection.</p>

  1159. <p><em>sock</em> must be a non-blocking socket.</p>

  1160. <div class="versionchanged">

  1161. <p><span class="versionmodified changed">Changed in version 3.7: </span>Even though the method was always documented as a coroutine

  1162. method, before Python 3.7 it returned a <a class="reference internal" href="asyncio-future.html#asyncio.Future" title="asyncio.Future"><code class="xref py py-class docutils literal notranslate"><span class="pre">Future</span></code></a>.

  1163. Since Python 3.7, this is an <code class="docutils literal notranslate"><span class="pre">async</span> <span class="pre">def</span></code> method.</p>

  1164. </div>

  1165. </dd></dl>

  1166. 

  1167. <dl class="py method">

  1168. <dt class="sig sig-object py" id="asyncio.loop.sock_sendto">

  1169. <em class="property"><span class="pre">coroutine</span> </em><span class="sig-prename descclassname"><span class="pre">loop.</span></span><span class="sig-name descname"><span class="pre">sock_sendto</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">sock</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">data</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">address</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.loop.sock_sendto" title="Link to this definition">¶</a></dt>

  1170. <dd><p>Send a datagram from <em>sock</em> to <em>address</em>.

  1171. Asynchronous version of

  1172. <a class="reference internal" href="socket.html#socket.socket.sendto" title="socket.socket.sendto"><code class="xref py py-meth docutils literal notranslate"><span class="pre">socket.sendto()</span></code></a>.</p>

  1173. <p>Return the number of bytes sent.</p>

  1174. <p><em>sock</em> must be a non-blocking socket.</p>

  1175. <div class="versionadded">

  1176. <p><span class="versionmodified added">New in version 3.11.</span></p>

  1177. </div>

  1178. </dd></dl>

  1179. 

  1180. <dl class="py method">

  1181. <dt class="sig sig-object py" id="asyncio.loop.sock_connect">

  1182. <em class="property"><span class="pre">coroutine</span> </em><span class="sig-prename descclassname"><span class="pre">loop.</span></span><span class="sig-name descname"><span class="pre">sock_connect</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">sock</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">address</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.loop.sock_connect" title="Link to this definition">¶</a></dt>

  1183. <dd><p>Connect <em>sock</em> to a remote socket at <em>address</em>.</p>

  1184. <p>Asynchronous version of <a class="reference internal" href="socket.html#socket.socket.connect" title="socket.socket.connect"><code class="xref py py-meth docutils literal notranslate"><span class="pre">socket.connect()</span></code></a>.</p>

  1185. <p><em>sock</em> must be a non-blocking socket.</p>

  1186. <div class="versionchanged">

  1187. <p><span class="versionmodified changed">Changed in version 3.5.2: </span><code class="docutils literal notranslate"><span class="pre">address</span></code> no longer needs to be resolved.  <code class="docutils literal notranslate"><span class="pre">sock_connect</span></code>

  1188. will try to check if the <em>address</em> is already resolved by calling

  1189. <a class="reference internal" href="socket.html#socket.inet_pton" title="socket.inet_pton"><code class="xref py py-func docutils literal notranslate"><span class="pre">socket.inet_pton()</span></code></a>.  If not,

  1190. <a class="reference internal" href="#asyncio.loop.getaddrinfo" title="asyncio.loop.getaddrinfo"><code class="xref py py-meth docutils literal notranslate"><span class="pre">loop.getaddrinfo()</span></code></a> will be used to resolve the

  1191. <em>address</em>.</p>

  1192. </div>

  1193. <div class="admonition seealso">

  1194. <p class="admonition-title">See also</p>

  1195. <p><a class="reference internal" href="#asyncio.loop.create_connection" title="asyncio.loop.create_connection"><code class="xref py py-meth docutils literal notranslate"><span class="pre">loop.create_connection()</span></code></a>

  1196. and  <a class="reference internal" href="asyncio-stream.html#asyncio.open_connection" title="asyncio.open_connection"><code class="xref py py-func docutils literal notranslate"><span class="pre">asyncio.open_connection()</span></code></a>.</p>

  1197. </div>

  1198. </dd></dl>

  1199. 

  1200. <dl class="py method">

  1201. <dt class="sig sig-object py" id="asyncio.loop.sock_accept">

  1202. <em class="property"><span class="pre">coroutine</span> </em><span class="sig-prename descclassname"><span class="pre">loop.</span></span><span class="sig-name descname"><span class="pre">sock_accept</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">sock</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.loop.sock_accept" title="Link to this definition">¶</a></dt>

  1203. <dd><p>Accept a connection.  Modeled after the blocking

  1204. <a class="reference internal" href="socket.html#socket.socket.accept" title="socket.socket.accept"><code class="xref py py-meth docutils literal notranslate"><span class="pre">socket.accept()</span></code></a> method.</p>

  1205. <p>The socket must be bound to an address and listening

  1206. for connections. The return value is a pair <code class="docutils literal notranslate"><span class="pre">(conn,</span> <span class="pre">address)</span></code> where <em>conn</em>

  1207. is a <em>new</em> socket object usable to send and receive data on the connection,

  1208. and <em>address</em> is the address bound to the socket on the other end of the

  1209. connection.</p>

  1210. <p><em>sock</em> must be a non-blocking socket.</p>

  1211. <div class="versionchanged">

  1212. <p><span class="versionmodified changed">Changed in version 3.7: </span>Even though the method was always documented as a coroutine

  1213. method, before Python 3.7 it returned a <a class="reference internal" href="asyncio-future.html#asyncio.Future" title="asyncio.Future"><code class="xref py py-class docutils literal notranslate"><span class="pre">Future</span></code></a>.

  1214. Since Python 3.7, this is an <code class="docutils literal notranslate"><span class="pre">async</span> <span class="pre">def</span></code> method.</p>

  1215. </div>

  1216. <div class="admonition seealso">

  1217. <p class="admonition-title">See also</p>

  1218. <p><a class="reference internal" href="#asyncio.loop.create_server" title="asyncio.loop.create_server"><code class="xref py py-meth docutils literal notranslate"><span class="pre">loop.create_server()</span></code></a> and <a class="reference internal" href="asyncio-stream.html#asyncio.start_server" title="asyncio.start_server"><code class="xref py py-func docutils literal notranslate"><span class="pre">start_server()</span></code></a>.</p>

  1219. </div>

  1220. </dd></dl>

  1221. 

  1222. <dl class="py method">

  1223. <dt class="sig sig-object py" id="asyncio.loop.sock_sendfile">

  1224. <em class="property"><span class="pre">coroutine</span> </em><span class="sig-prename descclassname"><span class="pre">loop.</span></span><span class="sig-name descname"><span class="pre">sock_sendfile</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">sock</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">file</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">offset</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">0</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">count</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em>, <em class="sig-param"><span class="o"><span class="pre">*</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">fallback</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">True</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.loop.sock_sendfile" title="Link to this definition">¶</a></dt>

  1225. <dd><p>Send a file using high-performance <a class="reference internal" href="os.html#os.sendfile" title="os.sendfile"><code class="xref py py-mod docutils literal notranslate"><span class="pre">os.sendfile</span></code></a> if possible.

  1226. Return the total number of bytes sent.</p>

  1227. <p>Asynchronous version of <a class="reference internal" href="socket.html#socket.socket.sendfile" title="socket.socket.sendfile"><code class="xref py py-meth docutils literal notranslate"><span class="pre">socket.sendfile()</span></code></a>.</p>

  1228. <p><em>sock</em> must be a non-blocking <a class="reference internal" href="socket.html#socket.SOCK_STREAM" title="socket.SOCK_STREAM"><code class="xref py py-const docutils literal notranslate"><span class="pre">socket.SOCK_STREAM</span></code></a>

  1229. <a class="reference internal" href="socket.html#socket.socket" title="socket.socket"><code class="xref py py-class docutils literal notranslate"><span class="pre">socket</span></code></a>.</p>

  1230. <p><em>file</em> must be a regular file object open in binary mode.</p>

  1231. <p><em>offset</em> tells from where to start reading the file. If specified,

  1232. <em>count</em> is the total number of bytes to transmit as opposed to

  1233. sending the file until EOF is reached. File position is always updated,

  1234. even when this method raises an error, and

  1235. <a class="reference internal" href="io.html#io.IOBase.tell" title="io.IOBase.tell"><code class="xref py py-meth docutils literal notranslate"><span class="pre">file.tell()</span></code></a> can be used to obtain the actual

  1236. number of bytes sent.</p>

  1237. <p><em>fallback</em>, when set to <code class="docutils literal notranslate"><span class="pre">True</span></code>, makes asyncio manually read and send

  1238. the file when the platform does not support the sendfile syscall

  1239. (e.g. Windows or SSL socket on Unix).</p>

  1240. <p>Raise <a class="reference internal" href="asyncio-exceptions.html#asyncio.SendfileNotAvailableError" title="asyncio.SendfileNotAvailableError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">SendfileNotAvailableError</span></code></a> if the system does not support

  1241. <em>sendfile</em> syscall and <em>fallback</em> is <code class="docutils literal notranslate"><span class="pre">False</span></code>.</p>

  1242. <p><em>sock</em> must be a non-blocking socket.</p>

  1243. <div class="versionadded">

  1244. <p><span class="versionmodified added">New in version 3.7.</span></p>

  1245. </div>

  1246. </dd></dl>

  1247. 

  1248. </section>

  1249. <section id="dns">

  1250. <h3><a class="toc-backref" href="#id11" role="doc-backlink">DNS</a><a class="headerlink" href="#dns" title="Link to this heading">¶</a></h3>

  1251. <dl class="py method">

  1252. <dt class="sig sig-object py" id="asyncio.loop.getaddrinfo">

  1253. <em class="property"><span class="pre">coroutine</span> </em><span class="sig-prename descclassname"><span class="pre">loop.</span></span><span class="sig-name descname"><span class="pre">getaddrinfo</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">host</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">port</span></span></em>, <em class="sig-param"><span class="o"><span class="pre">*</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">family</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">0</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">type</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">0</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">proto</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">0</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">flags</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">0</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.loop.getaddrinfo" title="Link to this definition">¶</a></dt>

  1254. <dd><p>Asynchronous version of <a class="reference internal" href="socket.html#socket.getaddrinfo" title="socket.getaddrinfo"><code class="xref py py-meth docutils literal notranslate"><span class="pre">socket.getaddrinfo()</span></code></a>.</p>

  1255. </dd></dl>

  1256. 

  1257. <dl class="py method">

  1258. <dt class="sig sig-object py" id="asyncio.loop.getnameinfo">

  1259. <em class="property"><span class="pre">coroutine</span> </em><span class="sig-prename descclassname"><span class="pre">loop.</span></span><span class="sig-name descname"><span class="pre">getnameinfo</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">sockaddr</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">flags</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">0</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.loop.getnameinfo" title="Link to this definition">¶</a></dt>

  1260. <dd><p>Asynchronous version of <a class="reference internal" href="socket.html#socket.getnameinfo" title="socket.getnameinfo"><code class="xref py py-meth docutils literal notranslate"><span class="pre">socket.getnameinfo()</span></code></a>.</p>

  1261. </dd></dl>

  1262. 

  1263. <div class="versionchanged">

  1264. <p><span class="versionmodified changed">Changed in version 3.7: </span>Both <em>getaddrinfo</em> and <em>getnameinfo</em> methods were always documented

  1265. to return a coroutine, but prior to Python 3.7 they were, in fact,

  1266. returning <a class="reference internal" href="asyncio-future.html#asyncio.Future" title="asyncio.Future"><code class="xref py py-class docutils literal notranslate"><span class="pre">asyncio.Future</span></code></a> objects.  Starting with Python 3.7

  1267. both methods are coroutines.</p>

  1268. </div>

  1269. </section>

  1270. <section id="working-with-pipes">

  1271. <h3><a class="toc-backref" href="#id12" role="doc-backlink">Working with pipes</a><a class="headerlink" href="#working-with-pipes" title="Link to this heading">¶</a></h3>

  1272. <dl class="py method">

  1273. <dt class="sig sig-object py" id="asyncio.loop.connect_read_pipe">

  1274. <em class="property"><span class="pre">coroutine</span> </em><span class="sig-prename descclassname"><span class="pre">loop.</span></span><span class="sig-name descname"><span class="pre">connect_read_pipe</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">protocol_factory</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">pipe</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.loop.connect_read_pipe" title="Link to this definition">¶</a></dt>

  1275. <dd><p>Register the read end of <em>pipe</em> in the event loop.</p>

  1276. <p><em>protocol_factory</em> must be a callable returning an

  1277. <a class="reference internal" href="asyncio-protocol.html#asyncio-protocol"><span class="std std-ref">asyncio protocol</span></a> implementation.</p>

  1278. <p><em>pipe</em> is a <a class="reference internal" href="../glossary.html#term-file-object"><span class="xref std std-term">file-like object</span></a>.</p>

  1279. <p>Return pair <code class="docutils literal notranslate"><span class="pre">(transport,</span> <span class="pre">protocol)</span></code>, where <em>transport</em> supports

  1280. the <a class="reference internal" href="asyncio-protocol.html#asyncio.ReadTransport" title="asyncio.ReadTransport"><code class="xref py py-class docutils literal notranslate"><span class="pre">ReadTransport</span></code></a> interface and <em>protocol</em> is an object

  1281. instantiated by the <em>protocol_factory</em>.</p>

  1282. <p>With <a class="reference internal" href="#asyncio.SelectorEventLoop" title="asyncio.SelectorEventLoop"><code class="xref py py-class docutils literal notranslate"><span class="pre">SelectorEventLoop</span></code></a> event loop, the <em>pipe</em> is set to

  1283. non-blocking mode.</p>

  1284. </dd></dl>

  1285. 

  1286. <dl class="py method">

  1287. <dt class="sig sig-object py" id="asyncio.loop.connect_write_pipe">

  1288. <em class="property"><span class="pre">coroutine</span> </em><span class="sig-prename descclassname"><span class="pre">loop.</span></span><span class="sig-name descname"><span class="pre">connect_write_pipe</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">protocol_factory</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">pipe</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.loop.connect_write_pipe" title="Link to this definition">¶</a></dt>

  1289. <dd><p>Register the write end of <em>pipe</em> in the event loop.</p>

  1290. <p><em>protocol_factory</em> must be a callable returning an

  1291. <a class="reference internal" href="asyncio-protocol.html#asyncio-protocol"><span class="std std-ref">asyncio protocol</span></a> implementation.</p>

  1292. <p><em>pipe</em> is <a class="reference internal" href="../glossary.html#term-file-object"><span class="xref std std-term">file-like object</span></a>.</p>

  1293. <p>Return pair <code class="docutils literal notranslate"><span class="pre">(transport,</span> <span class="pre">protocol)</span></code>, where <em>transport</em> supports

  1294. <a class="reference internal" href="asyncio-protocol.html#asyncio.WriteTransport" title="asyncio.WriteTransport"><code class="xref py py-class docutils literal notranslate"><span class="pre">WriteTransport</span></code></a> interface and <em>protocol</em> is an object

  1295. instantiated by the <em>protocol_factory</em>.</p>

  1296. <p>With <a class="reference internal" href="#asyncio.SelectorEventLoop" title="asyncio.SelectorEventLoop"><code class="xref py py-class docutils literal notranslate"><span class="pre">SelectorEventLoop</span></code></a> event loop, the <em>pipe</em> is set to

  1297. non-blocking mode.</p>

  1298. </dd></dl>

  1299. 

  1300. <div class="admonition note">

  1301. <p class="admonition-title">Note</p>

  1302. <p><a class="reference internal" href="#asyncio.SelectorEventLoop" title="asyncio.SelectorEventLoop"><code class="xref py py-class docutils literal notranslate"><span class="pre">SelectorEventLoop</span></code></a> does not support the above methods on

  1303. Windows.  Use <a class="reference internal" href="#asyncio.ProactorEventLoop" title="asyncio.ProactorEventLoop"><code class="xref py py-class docutils literal notranslate"><span class="pre">ProactorEventLoop</span></code></a> instead for Windows.</p>

  1304. </div>

  1305. <div class="admonition seealso">

  1306. <p class="admonition-title">See also</p>

  1307. <p>The <a class="reference internal" href="#asyncio.loop.subprocess_exec" title="asyncio.loop.subprocess_exec"><code class="xref py py-meth docutils literal notranslate"><span class="pre">loop.subprocess_exec()</span></code></a> and

  1308. <a class="reference internal" href="#asyncio.loop.subprocess_shell" title="asyncio.loop.subprocess_shell"><code class="xref py py-meth docutils literal notranslate"><span class="pre">loop.subprocess_shell()</span></code></a> methods.</p>

  1309. </div>

  1310. </section>

  1311. <section id="unix-signals">

  1312. <h3><a class="toc-backref" href="#id13" role="doc-backlink">Unix signals</a><a class="headerlink" href="#unix-signals" title="Link to this heading">¶</a></h3>

  1313. <dl class="py method" id="loop-add-signal-handler">

  1314. <dt class="sig sig-object py" id="asyncio.loop.add_signal_handler">

  1315. <span class="sig-prename descclassname"><span class="pre">loop.</span></span><span class="sig-name descname"><span class="pre">add_signal_handler</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">signum</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">callback</span></span></em>, <em class="sig-param"><span class="o"><span class="pre">*</span></span><span class="n"><span class="pre">args</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.loop.add_signal_handler" title="Link to this definition">¶</a></dt>

  1316. <dd><p>Set <em>callback</em> as the handler for the <em>signum</em> signal.</p>

  1317. <p>The callback will be invoked by <em>loop</em>, along with other queued callbacks

  1318. and runnable coroutines of that event loop. Unlike signal handlers

  1319. registered using <a class="reference internal" href="signal.html#signal.signal" title="signal.signal"><code class="xref py py-func docutils literal notranslate"><span class="pre">signal.signal()</span></code></a>, a callback registered with this

  1320. function is allowed to interact with the event loop.</p>

  1321. <p>Raise <a class="reference internal" href="exceptions.html#ValueError" title="ValueError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">ValueError</span></code></a> if the signal number is invalid or uncatchable.

  1322. Raise <a class="reference internal" href="exceptions.html#RuntimeError" title="RuntimeError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">RuntimeError</span></code></a> if there is a problem setting up the handler.</p>

  1323. <p>Use <a class="reference internal" href="functools.html#functools.partial" title="functools.partial"><code class="xref py py-func docutils literal notranslate"><span class="pre">functools.partial()</span></code></a> <a class="reference internal" href="#asyncio-pass-keywords"><span class="std std-ref">to pass keyword arguments</span></a> to <em>callback</em>.</p>

  1324. <p>Like <a class="reference internal" href="signal.html#signal.signal" title="signal.signal"><code class="xref py py-func docutils literal notranslate"><span class="pre">signal.signal()</span></code></a>, this function must be invoked in the main

  1325. thread.</p>

  1326. </dd></dl>

  1327. 

  1328. <dl class="py method">

  1329. <dt class="sig sig-object py" id="asyncio.loop.remove_signal_handler">

  1330. <span class="sig-prename descclassname"><span class="pre">loop.</span></span><span class="sig-name descname"><span class="pre">remove_signal_handler</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">sig</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.loop.remove_signal_handler" title="Link to this definition">¶</a></dt>

  1331. <dd><p>Remove the handler for the <em>sig</em> signal.</p>

  1332. <p>Return <code class="docutils literal notranslate"><span class="pre">True</span></code> if the signal handler was removed, or <code class="docutils literal notranslate"><span class="pre">False</span></code> if

  1333. no handler was set for the given signal.</p>

  1334. <div class="availability docutils container">

  1335. <p><a class="reference internal" href="intro.html#availability"><span class="std std-ref">Availability</span></a>: Unix.</p>

  1336. </div>

  1337. </dd></dl>

  1338. 

  1339. <div class="admonition seealso">

  1340. <p class="admonition-title">See also</p>

  1341. <p>The <a class="reference internal" href="signal.html#module-signal" title="signal: Set handlers for asynchronous events."><code class="xref py py-mod docutils literal notranslate"><span class="pre">signal</span></code></a> module.</p>

  1342. </div>

  1343. </section>

  1344. <section id="executing-code-in-thread-or-process-pools">

  1345. <h3><a class="toc-backref" href="#id14" role="doc-backlink">Executing code in thread or process pools</a><a class="headerlink" href="#executing-code-in-thread-or-process-pools" title="Link to this heading">¶</a></h3>

  1346. <dl class="py method">

  1347. <dt class="sig sig-object py" id="asyncio.loop.run_in_executor">

  1348. <em class="property"><span class="pre">awaitable</span> </em><span class="sig-prename descclassname"><span class="pre">loop.</span></span><span class="sig-name descname"><span class="pre">run_in_executor</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">executor</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">func</span></span></em>, <em class="sig-param"><span class="o"><span class="pre">*</span></span><span class="n"><span class="pre">args</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.loop.run_in_executor" title="Link to this definition">¶</a></dt>

  1349. <dd><p>Arrange for <em>func</em> to be called in the specified executor.</p>

  1350. <p>The <em>executor</em> argument should be an <a class="reference internal" href="concurrent.futures.html#concurrent.futures.Executor" title="concurrent.futures.Executor"><code class="xref py py-class docutils literal notranslate"><span class="pre">concurrent.futures.Executor</span></code></a>

  1351. instance. The default executor is used if <em>executor</em> is <code class="docutils literal notranslate"><span class="pre">None</span></code>.</p>

  1352. <p>Example:</p>

  1353. <div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="kn">import</span> <span class="nn">asyncio</span>

  1354. <span class="kn">import</span> <span class="nn">concurrent.futures</span>

  1355. 

  1356. <span class="k">def</span> <span class="nf">blocking_io</span><span class="p">():</span>

  1357.     <span class="c1"># File operations (such as logging) can block the</span>

  1358.     <span class="c1"># event loop: run them in a thread pool.</span>

  1359.     <span class="k">with</span> <span class="nb">open</span><span class="p">(</span><span class="s1">&#39;/dev/urandom&#39;</span><span class="p">,</span> <span class="s1">&#39;rb&#39;</span><span class="p">)</span> <span class="k">as</span> <span class="n">f</span><span class="p">:</span>

  1360.         <span class="k">return</span> <span class="n">f</span><span class="o">.</span><span class="n">read</span><span class="p">(</span><span class="mi">100</span><span class="p">)</span>

  1361. 

  1362. <span class="k">def</span> <span class="nf">cpu_bound</span><span class="p">():</span>

  1363.     <span class="c1"># CPU-bound operations will block the event loop:</span>

  1364.     <span class="c1"># in general it is preferable to run them in a</span>

  1365.     <span class="c1"># process pool.</span>

  1366.     <span class="k">return</span> <span class="nb">sum</span><span class="p">(</span><span class="n">i</span> <span class="o">*</span> <span class="n">i</span> <span class="k">for</span> <span class="n">i</span> <span class="ow">in</span> <span class="nb">range</span><span class="p">(</span><span class="mi">10</span> <span class="o">**</span> <span class="mi">7</span><span class="p">))</span>

  1367. 

  1368. <span class="k">async</span> <span class="k">def</span> <span class="nf">main</span><span class="p">():</span>

  1369.     <span class="n">loop</span> <span class="o">=</span> <span class="n">asyncio</span><span class="o">.</span><span class="n">get_running_loop</span><span class="p">()</span>

  1370. 

  1371.     <span class="c1">## Options:</span>

  1372. 

  1373.     <span class="c1"># 1. Run in the default loop&#39;s executor:</span>

  1374.     <span class="n">result</span> <span class="o">=</span> <span class="k">await</span> <span class="n">loop</span><span class="o">.</span><span class="n">run_in_executor</span><span class="p">(</span>

  1375.         <span class="kc">None</span><span class="p">,</span> <span class="n">blocking_io</span><span class="p">)</span>

  1376.     <span class="nb">print</span><span class="p">(</span><span class="s1">&#39;default thread pool&#39;</span><span class="p">,</span> <span class="n">result</span><span class="p">)</span>

  1377. 

  1378.     <span class="c1"># 2. Run in a custom thread pool:</span>

  1379.     <span class="k">with</span> <span class="n">concurrent</span><span class="o">.</span><span class="n">futures</span><span class="o">.</span><span class="n">ThreadPoolExecutor</span><span class="p">()</span> <span class="k">as</span> <span class="n">pool</span><span class="p">:</span>

  1380.         <span class="n">result</span> <span class="o">=</span> <span class="k">await</span> <span class="n">loop</span><span class="o">.</span><span class="n">run_in_executor</span><span class="p">(</span>

  1381.             <span class="n">pool</span><span class="p">,</span> <span class="n">blocking_io</span><span class="p">)</span>

  1382.         <span class="nb">print</span><span class="p">(</span><span class="s1">&#39;custom thread pool&#39;</span><span class="p">,</span> <span class="n">result</span><span class="p">)</span>

  1383. 

  1384.     <span class="c1"># 3. Run in a custom process pool:</span>

  1385.     <span class="k">with</span> <span class="n">concurrent</span><span class="o">.</span><span class="n">futures</span><span class="o">.</span><span class="n">ProcessPoolExecutor</span><span class="p">()</span> <span class="k">as</span> <span class="n">pool</span><span class="p">:</span>

  1386.         <span class="n">result</span> <span class="o">=</span> <span class="k">await</span> <span class="n">loop</span><span class="o">.</span><span class="n">run_in_executor</span><span class="p">(</span>

  1387.             <span class="n">pool</span><span class="p">,</span> <span class="n">cpu_bound</span><span class="p">)</span>

  1388.         <span class="nb">print</span><span class="p">(</span><span class="s1">&#39;custom process pool&#39;</span><span class="p">,</span> <span class="n">result</span><span class="p">)</span>

  1389. 

  1390. <span class="k">if</span> <span class="vm">__name__</span> <span class="o">==</span> <span class="s1">&#39;__main__&#39;</span><span class="p">:</span>

  1391.     <span class="n">asyncio</span><span class="o">.</span><span class="n">run</span><span class="p">(</span><span class="n">main</span><span class="p">())</span>

  1392. </pre></div>

  1393. </div>

  1394. <p>Note that the entry point guard (<code class="docutils literal notranslate"><span class="pre">if</span> <span class="pre">__name__</span> <span class="pre">==</span> <span class="pre">'__main__'</span></code>)

  1395. is required for option 3 due to the peculiarities of <a class="reference internal" href="multiprocessing.html#module-multiprocessing" title="multiprocessing: Process-based parallelism."><code class="xref py py-mod docutils literal notranslate"><span class="pre">multiprocessing</span></code></a>,

  1396. which is used by <a class="reference internal" href="concurrent.futures.html#concurrent.futures.ProcessPoolExecutor" title="concurrent.futures.ProcessPoolExecutor"><code class="xref py py-class docutils literal notranslate"><span class="pre">ProcessPoolExecutor</span></code></a>.

  1397. See <a class="reference internal" href="multiprocessing.html#multiprocessing-safe-main-import"><span class="std std-ref">Safe importing of main module</span></a>.</p>

  1398. <p>This method returns a <a class="reference internal" href="asyncio-future.html#asyncio.Future" title="asyncio.Future"><code class="xref py py-class docutils literal notranslate"><span class="pre">asyncio.Future</span></code></a> object.</p>

  1399. <p>Use <a class="reference internal" href="functools.html#functools.partial" title="functools.partial"><code class="xref py py-func docutils literal notranslate"><span class="pre">functools.partial()</span></code></a> <a class="reference internal" href="#asyncio-pass-keywords"><span class="std std-ref">to pass keyword arguments</span></a> to <em>func</em>.</p>

  1400. <div class="versionchanged">

  1401. <p><span class="versionmodified changed">Changed in version 3.5.3: </span><a class="reference internal" href="#asyncio.loop.run_in_executor" title="asyncio.loop.run_in_executor"><code class="xref py py-meth docutils literal notranslate"><span class="pre">loop.run_in_executor()</span></code></a> no longer configures the

  1402. <code class="docutils literal notranslate"><span class="pre">max_workers</span></code> of the thread pool executor it creates, instead

  1403. leaving it up to the thread pool executor

  1404. (<a class="reference internal" href="concurrent.futures.html#concurrent.futures.ThreadPoolExecutor" title="concurrent.futures.ThreadPoolExecutor"><code class="xref py py-class docutils literal notranslate"><span class="pre">ThreadPoolExecutor</span></code></a>) to set the

  1405. default.</p>

  1406. </div>

  1407. </dd></dl>

  1408. 

  1409. <dl class="py method">

  1410. <dt class="sig sig-object py" id="asyncio.loop.set_default_executor">

  1411. <span class="sig-prename descclassname"><span class="pre">loop.</span></span><span class="sig-name descname"><span class="pre">set_default_executor</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">executor</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.loop.set_default_executor" title="Link to this definition">¶</a></dt>

  1412. <dd><p>Set <em>executor</em> as the default executor used by <a class="reference internal" href="#asyncio.loop.run_in_executor" title="asyncio.loop.run_in_executor"><code class="xref py py-meth docutils literal notranslate"><span class="pre">run_in_executor()</span></code></a>.

  1413. <em>executor</em> must be an instance of

  1414. <a class="reference internal" href="concurrent.futures.html#concurrent.futures.ThreadPoolExecutor" title="concurrent.futures.ThreadPoolExecutor"><code class="xref py py-class docutils literal notranslate"><span class="pre">ThreadPoolExecutor</span></code></a>.</p>

  1415. <div class="versionchanged">

  1416. <p><span class="versionmodified changed">Changed in version 3.11: </span><em>executor</em> must be an instance of

  1417. <a class="reference internal" href="concurrent.futures.html#concurrent.futures.ThreadPoolExecutor" title="concurrent.futures.ThreadPoolExecutor"><code class="xref py py-class docutils literal notranslate"><span class="pre">ThreadPoolExecutor</span></code></a>.</p>

  1418. </div>

  1419. </dd></dl>

  1420. 

  1421. </section>

  1422. <section id="error-handling-api">

  1423. <h3><a class="toc-backref" href="#id15" role="doc-backlink">Error Handling API</a><a class="headerlink" href="#error-handling-api" title="Link to this heading">¶</a></h3>

  1424. <p>Allows customizing how exceptions are handled in the event loop.</p>

  1425. <dl class="py method">

  1426. <dt class="sig sig-object py" id="asyncio.loop.set_exception_handler">

  1427. <span class="sig-prename descclassname"><span class="pre">loop.</span></span><span class="sig-name descname"><span class="pre">set_exception_handler</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">handler</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.loop.set_exception_handler" title="Link to this definition">¶</a></dt>

  1428. <dd><p>Set <em>handler</em> as the new event loop exception handler.</p>

  1429. <p>If <em>handler</em> is <code class="docutils literal notranslate"><span class="pre">None</span></code>, the default exception handler will

  1430. be set.  Otherwise, <em>handler</em> must be a callable with the signature

  1431. matching <code class="docutils literal notranslate"><span class="pre">(loop,</span> <span class="pre">context)</span></code>, where <code class="docutils literal notranslate"><span class="pre">loop</span></code>

  1432. is a reference to the active event loop, and <code class="docutils literal notranslate"><span class="pre">context</span></code>

  1433. is a <code class="docutils literal notranslate"><span class="pre">dict</span></code> object containing the details of the exception

  1434. (see <a class="reference internal" href="#asyncio.loop.call_exception_handler" title="asyncio.loop.call_exception_handler"><code class="xref py py-meth docutils literal notranslate"><span class="pre">call_exception_handler()</span></code></a> documentation for details

  1435. about context).</p>

  1436. <p>If the handler is called on behalf of a <a class="reference internal" href="asyncio-task.html#asyncio.Task" title="asyncio.Task"><code class="xref py py-class docutils literal notranslate"><span class="pre">Task</span></code></a> or

  1437. <a class="reference internal" href="#asyncio.Handle" title="asyncio.Handle"><code class="xref py py-class docutils literal notranslate"><span class="pre">Handle</span></code></a>, it is run in the

  1438. <a class="reference internal" href="contextvars.html#contextvars.Context" title="contextvars.Context"><code class="xref py py-class docutils literal notranslate"><span class="pre">contextvars.Context</span></code></a> of that task or callback handle.</p>

  1439. <div class="versionchanged">

  1440. <p><span class="versionmodified changed">Changed in version 3.12: </span>The handler may be called in the <a class="reference internal" href="contextvars.html#contextvars.Context" title="contextvars.Context"><code class="xref py py-class docutils literal notranslate"><span class="pre">Context</span></code></a>

  1441. of the task or handle where the exception originated.</p>

  1442. </div>

  1443. </dd></dl>

  1444. 

  1445. <dl class="py method">

  1446. <dt class="sig sig-object py" id="asyncio.loop.get_exception_handler">

  1447. <span class="sig-prename descclassname"><span class="pre">loop.</span></span><span class="sig-name descname"><span class="pre">get_exception_handler</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.loop.get_exception_handler" title="Link to this definition">¶</a></dt>

  1448. <dd><p>Return the current exception handler, or <code class="docutils literal notranslate"><span class="pre">None</span></code> if no custom

  1449. exception handler was set.</p>

  1450. <div class="versionadded">

  1451. <p><span class="versionmodified added">New in version 3.5.2.</span></p>

  1452. </div>

  1453. </dd></dl>

  1454. 

  1455. <dl class="py method">

  1456. <dt class="sig sig-object py" id="asyncio.loop.default_exception_handler">

  1457. <span class="sig-prename descclassname"><span class="pre">loop.</span></span><span class="sig-name descname"><span class="pre">default_exception_handler</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">context</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.loop.default_exception_handler" title="Link to this definition">¶</a></dt>

  1458. <dd><p>Default exception handler.</p>

  1459. <p>This is called when an exception occurs and no exception

  1460. handler is set. This can be called by a custom exception

  1461. handler that wants to defer to the default handler behavior.</p>

  1462. <p><em>context</em> parameter has the same meaning as in

  1463. <a class="reference internal" href="#asyncio.loop.call_exception_handler" title="asyncio.loop.call_exception_handler"><code class="xref py py-meth docutils literal notranslate"><span class="pre">call_exception_handler()</span></code></a>.</p>

  1464. </dd></dl>

  1465. 

  1466. <dl class="py method">

  1467. <dt class="sig sig-object py" id="asyncio.loop.call_exception_handler">

  1468. <span class="sig-prename descclassname"><span class="pre">loop.</span></span><span class="sig-name descname"><span class="pre">call_exception_handler</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">context</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.loop.call_exception_handler" title="Link to this definition">¶</a></dt>

  1469. <dd><p>Call the current event loop exception handler.</p>

  1470. <p><em>context</em> is a <code class="docutils literal notranslate"><span class="pre">dict</span></code> object containing the following keys

  1471. (new keys may be introduced in future Python versions):</p>

  1472. <ul class="simple">

  1473. <li><p>‘message’: Error message;</p></li>

  1474. <li><p>‘exception’ (optional): Exception object;</p></li>

  1475. <li><p>‘future’ (optional): <a class="reference internal" href="asyncio-future.html#asyncio.Future" title="asyncio.Future"><code class="xref py py-class docutils literal notranslate"><span class="pre">asyncio.Future</span></code></a> instance;</p></li>

  1476. <li><p>‘task’ (optional): <a class="reference internal" href="asyncio-task.html#asyncio.Task" title="asyncio.Task"><code class="xref py py-class docutils literal notranslate"><span class="pre">asyncio.Task</span></code></a> instance;</p></li>

  1477. <li><p>‘handle’ (optional): <a class="reference internal" href="#asyncio.Handle" title="asyncio.Handle"><code class="xref py py-class docutils literal notranslate"><span class="pre">asyncio.Handle</span></code></a> instance;</p></li>

  1478. <li><p>‘protocol’ (optional): <a class="reference internal" href="asyncio-protocol.html#asyncio-protocol"><span class="std std-ref">Protocol</span></a> instance;</p></li>

  1479. <li><p>‘transport’ (optional): <a class="reference internal" href="asyncio-protocol.html#asyncio-transport"><span class="std std-ref">Transport</span></a> instance;</p></li>

  1480. <li><p>‘socket’ (optional): <a class="reference internal" href="socket.html#socket.socket" title="socket.socket"><code class="xref py py-class docutils literal notranslate"><span class="pre">socket.socket</span></code></a> instance;</p></li>

  1481. <li><dl class="simple">

  1482. <dt>‘asyncgen’ (optional): Asynchronous generator that caused</dt><dd><p>the exception.</p>

  1483. </dd>

  1484. </dl>

  1485. </li>

  1486. </ul>

  1487. <div class="admonition note">

  1488. <p class="admonition-title">Note</p>

  1489. <p>This method should not be overloaded in subclassed

  1490. event loops.  For custom exception handling, use

  1491. the <a class="reference internal" href="#asyncio.loop.set_exception_handler" title="asyncio.loop.set_exception_handler"><code class="xref py py-meth docutils literal notranslate"><span class="pre">set_exception_handler()</span></code></a> method.</p>

  1492. </div>

  1493. </dd></dl>

  1494. 

  1495. </section>

  1496. <section id="enabling-debug-mode">

  1497. <h3><a class="toc-backref" href="#id16" role="doc-backlink">Enabling debug mode</a><a class="headerlink" href="#enabling-debug-mode" title="Link to this heading">¶</a></h3>

  1498. <dl class="py method">

  1499. <dt class="sig sig-object py" id="asyncio.loop.get_debug">

  1500. <span class="sig-prename descclassname"><span class="pre">loop.</span></span><span class="sig-name descname"><span class="pre">get_debug</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.loop.get_debug" title="Link to this definition">¶</a></dt>

  1501. <dd><p>Get the debug mode (<a class="reference internal" href="functions.html#bool" title="bool"><code class="xref py py-class docutils literal notranslate"><span class="pre">bool</span></code></a>) of the event loop.</p>

  1502. <p>The default value is <code class="docutils literal notranslate"><span class="pre">True</span></code> if the environment variable

  1503. <span class="target" id="index-5"></span><a class="reference internal" href="../using/cmdline.html#envvar-PYTHONASYNCIODEBUG"><code class="xref std std-envvar docutils literal notranslate"><span class="pre">PYTHONASYNCIODEBUG</span></code></a> is set to a non-empty string, <code class="docutils literal notranslate"><span class="pre">False</span></code>

  1504. otherwise.</p>

  1505. </dd></dl>

  1506. 

  1507. <dl class="py method">

  1508. <dt class="sig sig-object py" id="asyncio.loop.set_debug">

  1509. <span class="sig-prename descclassname"><span class="pre">loop.</span></span><span class="sig-name descname"><span class="pre">set_debug</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">enabled</span></span><span class="p"><span class="pre">:</span></span><span class="w"> </span><span class="n"><a class="reference internal" href="functions.html#bool" title="bool"><span class="pre">bool</span></a></span></em><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.loop.set_debug" title="Link to this definition">¶</a></dt>

  1510. <dd><p>Set the debug mode of the event loop.</p>

  1511. <div class="versionchanged">

  1512. <p><span class="versionmodified changed">Changed in version 3.7: </span>The new <a class="reference internal" href="devmode.html#devmode"><span class="std std-ref">Python Development Mode</span></a> can now also be used

  1513. to enable the debug mode.</p>

  1514. </div>

  1515. </dd></dl>

  1516. 

  1517. <dl class="py attribute">

  1518. <dt class="sig sig-object py" id="asyncio.loop.slow_callback_duration">

  1519. <span class="sig-prename descclassname"><span class="pre">loop.</span></span><span class="sig-name descname"><span class="pre">slow_callback_duration</span></span><a class="headerlink" href="#asyncio.loop.slow_callback_duration" title="Link to this definition">¶</a></dt>

  1520. <dd><p>This attribute can be used to set the

  1521. minimum execution duration in seconds that is considered “slow”.

  1522. When debug mode is enabled, “slow” callbacks are logged.</p>

  1523. <p>Default value is 100 milliseconds.</p>

  1524. </dd></dl>

  1525. 

  1526. <div class="admonition seealso">

  1527. <p class="admonition-title">See also</p>

  1528. <p>The <a class="reference internal" href="asyncio-dev.html#asyncio-debug-mode"><span class="std std-ref">debug mode of asyncio</span></a>.</p>

  1529. </div>

  1530. </section>

  1531. <section id="running-subprocesses">

  1532. <h3><a class="toc-backref" href="#id17" role="doc-backlink">Running Subprocesses</a><a class="headerlink" href="#running-subprocesses" title="Link to this heading">¶</a></h3>

  1533. <p>Methods described in this subsections are low-level.  In regular

  1534. async/await code consider using the high-level

  1535. <a class="reference internal" href="asyncio-subprocess.html#asyncio.create_subprocess_shell" title="asyncio.create_subprocess_shell"><code class="xref py py-func docutils literal notranslate"><span class="pre">asyncio.create_subprocess_shell()</span></code></a> and

  1536. <a class="reference internal" href="asyncio-subprocess.html#asyncio.create_subprocess_exec" title="asyncio.create_subprocess_exec"><code class="xref py py-func docutils literal notranslate"><span class="pre">asyncio.create_subprocess_exec()</span></code></a> convenience functions instead.</p>

  1537. <div class="admonition note">

  1538. <p class="admonition-title">Note</p>

  1539. <p>On Windows, the default event loop <a class="reference internal" href="#asyncio.ProactorEventLoop" title="asyncio.ProactorEventLoop"><code class="xref py py-class docutils literal notranslate"><span class="pre">ProactorEventLoop</span></code></a> supports

  1540. subprocesses, whereas <a class="reference internal" href="#asyncio.SelectorEventLoop" title="asyncio.SelectorEventLoop"><code class="xref py py-class docutils literal notranslate"><span class="pre">SelectorEventLoop</span></code></a> does not. See

  1541. <a class="reference internal" href="asyncio-platforms.html#asyncio-windows-subprocess"><span class="std std-ref">Subprocess Support on Windows</span></a> for

  1542. details.</p>

  1543. </div>

  1544. <dl class="py method" id="loop-subprocess-exec">

  1545. <dt class="sig sig-object py" id="asyncio.loop.subprocess_exec">

  1546. <em class="property"><span class="pre">coroutine</span> </em><span class="sig-prename descclassname"><span class="pre">loop.</span></span><span class="sig-name descname"><span class="pre">subprocess_exec</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">protocol_factory</span></span></em>, <em class="sig-param"><span class="o"><span class="pre">*</span></span><span class="n"><span class="pre">args</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">stdin</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">subprocess.PIPE</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">stdout</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">subprocess.PIPE</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">stderr</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">subprocess.PIPE</span></span></em>, <em class="sig-param"><span class="o"><span class="pre">**</span></span><span class="n"><span class="pre">kwargs</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.loop.subprocess_exec" title="Link to this definition">¶</a></dt>

  1547. <dd><p>Create a subprocess from one or more string arguments specified by

  1548. <em>args</em>.</p>

  1549. <p><em>args</em> must be a list of strings represented by:</p>

  1550. <ul class="simple">

  1551. <li><p><a class="reference internal" href="stdtypes.html#str" title="str"><code class="xref py py-class docutils literal notranslate"><span class="pre">str</span></code></a>;</p></li>

  1552. <li><p>or <a class="reference internal" href="stdtypes.html#bytes" title="bytes"><code class="xref py py-class docutils literal notranslate"><span class="pre">bytes</span></code></a>, encoded to the

  1553. <a class="reference internal" href="os.html#filesystem-encoding"><span class="std std-ref">filesystem encoding</span></a>.</p></li>

  1554. </ul>

  1555. <p>The first string specifies the program executable,

  1556. and the remaining strings specify the arguments.  Together, string

  1557. arguments form the <code class="docutils literal notranslate"><span class="pre">argv</span></code> of the program.</p>

  1558. <p>This is similar to the standard library <a class="reference internal" href="subprocess.html#subprocess.Popen" title="subprocess.Popen"><code class="xref py py-class docutils literal notranslate"><span class="pre">subprocess.Popen</span></code></a>

  1559. class called with <code class="docutils literal notranslate"><span class="pre">shell=False</span></code> and the list of strings passed as

  1560. the first argument; however, where <a class="reference internal" href="subprocess.html#subprocess.Popen" title="subprocess.Popen"><code class="xref py py-class docutils literal notranslate"><span class="pre">Popen</span></code></a> takes

  1561. a single argument which is list of strings, <em>subprocess_exec</em>

  1562. takes multiple string arguments.</p>

  1563. <p>The <em>protocol_factory</em> must be a callable returning a subclass of the

  1564. <a class="reference internal" href="asyncio-protocol.html#asyncio.SubprocessProtocol" title="asyncio.SubprocessProtocol"><code class="xref py py-class docutils literal notranslate"><span class="pre">asyncio.SubprocessProtocol</span></code></a> class.</p>

  1565. <p>Other parameters:</p>

  1566. <ul>

  1567. <li><p><em>stdin</em> can be any of these:</p>

  1568. <ul class="simple">

  1569. <li><p>a file-like object</p></li>

  1570. <li><p>an existing file descriptor (a positive integer), for example those created with <a class="reference internal" href="os.html#os.pipe" title="os.pipe"><code class="xref py py-meth docutils literal notranslate"><span class="pre">os.pipe()</span></code></a></p></li>

  1571. <li><p>the <a class="reference internal" href="subprocess.html#subprocess.PIPE" title="subprocess.PIPE"><code class="xref py py-const docutils literal notranslate"><span class="pre">subprocess.PIPE</span></code></a> constant (default) which will create a new

  1572. pipe and connect it,</p></li>

  1573. <li><p>the value <code class="docutils literal notranslate"><span class="pre">None</span></code> which will make the subprocess inherit the file

  1574. descriptor from this process</p></li>

  1575. <li><p>the <a class="reference internal" href="subprocess.html#subprocess.DEVNULL" title="subprocess.DEVNULL"><code class="xref py py-const docutils literal notranslate"><span class="pre">subprocess.DEVNULL</span></code></a> constant which indicates that the

  1576. special <a class="reference internal" href="os.html#os.devnull" title="os.devnull"><code class="xref py py-data docutils literal notranslate"><span class="pre">os.devnull</span></code></a> file will be used</p></li>

  1577. </ul>

  1578. </li>

  1579. <li><p><em>stdout</em> can be any of these:</p>

  1580. <ul class="simple">

  1581. <li><p>a file-like object</p></li>

  1582. <li><p>the <a class="reference internal" href="subprocess.html#subprocess.PIPE" title="subprocess.PIPE"><code class="xref py py-const docutils literal notranslate"><span class="pre">subprocess.PIPE</span></code></a> constant (default) which will create a new

  1583. pipe and connect it,</p></li>

  1584. <li><p>the value <code class="docutils literal notranslate"><span class="pre">None</span></code> which will make the subprocess inherit the file

  1585. descriptor from this process</p></li>

  1586. <li><p>the <a class="reference internal" href="subprocess.html#subprocess.DEVNULL" title="subprocess.DEVNULL"><code class="xref py py-const docutils literal notranslate"><span class="pre">subprocess.DEVNULL</span></code></a> constant which indicates that the

  1587. special <a class="reference internal" href="os.html#os.devnull" title="os.devnull"><code class="xref py py-data docutils literal notranslate"><span class="pre">os.devnull</span></code></a> file will be used</p></li>

  1588. </ul>

  1589. </li>

  1590. <li><p><em>stderr</em> can be any of these:</p>

  1591. <ul class="simple">

  1592. <li><p>a file-like object</p></li>

  1593. <li><p>the <a class="reference internal" href="subprocess.html#subprocess.PIPE" title="subprocess.PIPE"><code class="xref py py-const docutils literal notranslate"><span class="pre">subprocess.PIPE</span></code></a> constant (default) which will create a new

  1594. pipe and connect it,</p></li>

  1595. <li><p>the value <code class="docutils literal notranslate"><span class="pre">None</span></code> which will make the subprocess inherit the file

  1596. descriptor from this process</p></li>

  1597. <li><p>the <a class="reference internal" href="subprocess.html#subprocess.DEVNULL" title="subprocess.DEVNULL"><code class="xref py py-const docutils literal notranslate"><span class="pre">subprocess.DEVNULL</span></code></a> constant which indicates that the

  1598. special <a class="reference internal" href="os.html#os.devnull" title="os.devnull"><code class="xref py py-data docutils literal notranslate"><span class="pre">os.devnull</span></code></a> file will be used</p></li>

  1599. <li><p>the <a class="reference internal" href="subprocess.html#subprocess.STDOUT" title="subprocess.STDOUT"><code class="xref py py-const docutils literal notranslate"><span class="pre">subprocess.STDOUT</span></code></a> constant which will connect the standard

  1600. error stream to the process’ standard output stream</p></li>

  1601. </ul>

  1602. </li>

  1603. <li><p>All other keyword arguments are passed to <a class="reference internal" href="subprocess.html#subprocess.Popen" title="subprocess.Popen"><code class="xref py py-class docutils literal notranslate"><span class="pre">subprocess.Popen</span></code></a>

  1604. without interpretation, except for <em>bufsize</em>, <em>universal_newlines</em>,

  1605. <em>shell</em>, <em>text</em>, <em>encoding</em> and <em>errors</em>, which should not be specified

  1606. at all.</p>

  1607. <p>The <code class="docutils literal notranslate"><span class="pre">asyncio</span></code> subprocess API does not support decoding the streams

  1608. as text. <a class="reference internal" href="stdtypes.html#bytes.decode" title="bytes.decode"><code class="xref py py-func docutils literal notranslate"><span class="pre">bytes.decode()</span></code></a> can be used to convert the bytes returned

  1609. from the stream to text.</p>

  1610. </li>

  1611. </ul>

  1612. <p>If a file-like object passed as <em>stdin</em>, <em>stdout</em> or <em>stderr</em> represents a

  1613. pipe, then the other side of this pipe should be registered with

  1614. <a class="reference internal" href="#asyncio.loop.connect_write_pipe" title="asyncio.loop.connect_write_pipe"><code class="xref py py-meth docutils literal notranslate"><span class="pre">connect_write_pipe()</span></code></a> or <a class="reference internal" href="#asyncio.loop.connect_read_pipe" title="asyncio.loop.connect_read_pipe"><code class="xref py py-meth docutils literal notranslate"><span class="pre">connect_read_pipe()</span></code></a> for use

  1615. with the event loop.</p>

  1616. <p>See the constructor of the <a class="reference internal" href="subprocess.html#subprocess.Popen" title="subprocess.Popen"><code class="xref py py-class docutils literal notranslate"><span class="pre">subprocess.Popen</span></code></a> class

  1617. for documentation on other arguments.</p>

  1618. <p>Returns a pair of <code class="docutils literal notranslate"><span class="pre">(transport,</span> <span class="pre">protocol)</span></code>, where <em>transport</em>

  1619. conforms to the <a class="reference internal" href="asyncio-protocol.html#asyncio.SubprocessTransport" title="asyncio.SubprocessTransport"><code class="xref py py-class docutils literal notranslate"><span class="pre">asyncio.SubprocessTransport</span></code></a> base class and

  1620. <em>protocol</em> is an object instantiated by the <em>protocol_factory</em>.</p>

  1621. </dd></dl>

  1622. 

  1623. <dl class="py method">

  1624. <dt class="sig sig-object py" id="asyncio.loop.subprocess_shell">

  1625. <em class="property"><span class="pre">coroutine</span> </em><span class="sig-prename descclassname"><span class="pre">loop.</span></span><span class="sig-name descname"><span class="pre">subprocess_shell</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">protocol_factory</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">cmd</span></span></em>, <em class="sig-param"><span class="o"><span class="pre">*</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">stdin</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">subprocess.PIPE</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">stdout</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">subprocess.PIPE</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">stderr</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">subprocess.PIPE</span></span></em>, <em class="sig-param"><span class="o"><span class="pre">**</span></span><span class="n"><span class="pre">kwargs</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.loop.subprocess_shell" title="Link to this definition">¶</a></dt>

  1626. <dd><p>Create a subprocess from <em>cmd</em>, which can be a <a class="reference internal" href="stdtypes.html#str" title="str"><code class="xref py py-class docutils literal notranslate"><span class="pre">str</span></code></a> or a

  1627. <a class="reference internal" href="stdtypes.html#bytes" title="bytes"><code class="xref py py-class docutils literal notranslate"><span class="pre">bytes</span></code></a> string encoded to the

  1628. <a class="reference internal" href="os.html#filesystem-encoding"><span class="std std-ref">filesystem encoding</span></a>,

  1629. using the platform’s “shell” syntax.</p>

  1630. <p>This is similar to the standard library <a class="reference internal" href="subprocess.html#subprocess.Popen" title="subprocess.Popen"><code class="xref py py-class docutils literal notranslate"><span class="pre">subprocess.Popen</span></code></a>

  1631. class called with <code class="docutils literal notranslate"><span class="pre">shell=True</span></code>.</p>

  1632. <p>The <em>protocol_factory</em> must be a callable returning a subclass of the

  1633. <a class="reference internal" href="asyncio-protocol.html#asyncio.SubprocessProtocol" title="asyncio.SubprocessProtocol"><code class="xref py py-class docutils literal notranslate"><span class="pre">SubprocessProtocol</span></code></a> class.</p>

  1634. <p>See <a class="reference internal" href="#asyncio.loop.subprocess_exec" title="asyncio.loop.subprocess_exec"><code class="xref py py-meth docutils literal notranslate"><span class="pre">subprocess_exec()</span></code></a> for more details about

  1635. the remaining arguments.</p>

  1636. <p>Returns a pair of <code class="docutils literal notranslate"><span class="pre">(transport,</span> <span class="pre">protocol)</span></code>, where <em>transport</em>

  1637. conforms to the <a class="reference internal" href="asyncio-protocol.html#asyncio.SubprocessTransport" title="asyncio.SubprocessTransport"><code class="xref py py-class docutils literal notranslate"><span class="pre">SubprocessTransport</span></code></a> base class and

  1638. <em>protocol</em> is an object instantiated by the <em>protocol_factory</em>.</p>

  1639. </dd></dl>

  1640. 

  1641. <div class="admonition note">

  1642. <p class="admonition-title">Note</p>

  1643. <p>It is the application’s responsibility to ensure that all whitespace

  1644. and special characters are quoted appropriately to avoid <a class="reference external" href="https://en.wikipedia.org/wiki/Shell_injection#Shell_injection">shell injection</a>

  1645. vulnerabilities. The <a class="reference internal" href="shlex.html#shlex.quote" title="shlex.quote"><code class="xref py py-func docutils literal notranslate"><span class="pre">shlex.quote()</span></code></a> function can be used to

  1646. properly escape whitespace and special characters in strings that

  1647. are going to be used to construct shell commands.</p>

  1648. </div>

  1649. </section>

  1650. </section>

  1651. <section id="callback-handles">

  1652. <h2>Callback Handles<a class="headerlink" href="#callback-handles" title="Link to this heading">¶</a></h2>

  1653. <dl class="py class">

  1654. <dt class="sig sig-object py" id="asyncio.Handle">

  1655. <em class="property"><span class="pre">class</span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">asyncio.</span></span><span class="sig-name descname"><span class="pre">Handle</span></span><a class="headerlink" href="#asyncio.Handle" title="Link to this definition">¶</a></dt>

  1656. <dd><p>A callback wrapper object returned by <a class="reference internal" href="#asyncio.loop.call_soon" title="asyncio.loop.call_soon"><code class="xref py py-meth docutils literal notranslate"><span class="pre">loop.call_soon()</span></code></a>,

  1657. <a class="reference internal" href="#asyncio.loop.call_soon_threadsafe" title="asyncio.loop.call_soon_threadsafe"><code class="xref py py-meth docutils literal notranslate"><span class="pre">loop.call_soon_threadsafe()</span></code></a>.</p>

  1658. <dl class="py method">

  1659. <dt class="sig sig-object py" id="asyncio.Handle.get_context">

  1660. <span class="sig-name descname"><span class="pre">get_context</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.Handle.get_context" title="Link to this definition">¶</a></dt>

  1661. <dd><p>Return the <a class="reference internal" href="contextvars.html#contextvars.Context" title="contextvars.Context"><code class="xref py py-class docutils literal notranslate"><span class="pre">contextvars.Context</span></code></a> object

  1662. associated with the handle.</p>

  1663. <div class="versionadded">

  1664. <p><span class="versionmodified added">New in version 3.12.</span></p>

  1665. </div>

  1666. </dd></dl>

  1667. 

  1668. <dl class="py method">

  1669. <dt class="sig sig-object py" id="asyncio.Handle.cancel">

  1670. <span class="sig-name descname"><span class="pre">cancel</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.Handle.cancel" title="Link to this definition">¶</a></dt>

  1671. <dd><p>Cancel the callback.  If the callback has already been canceled

  1672. or executed, this method has no effect.</p>

  1673. </dd></dl>

  1674. 

  1675. <dl class="py method">

  1676. <dt class="sig sig-object py" id="asyncio.Handle.cancelled">

  1677. <span class="sig-name descname"><span class="pre">cancelled</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.Handle.cancelled" title="Link to this definition">¶</a></dt>

  1678. <dd><p>Return <code class="docutils literal notranslate"><span class="pre">True</span></code> if the callback was cancelled.</p>

  1679. <div class="versionadded">

  1680. <p><span class="versionmodified added">New in version 3.7.</span></p>

  1681. </div>

  1682. </dd></dl>

  1683. 

  1684. </dd></dl>

  1685. 

  1686. <dl class="py class">

  1687. <dt class="sig sig-object py" id="asyncio.TimerHandle">

  1688. <em class="property"><span class="pre">class</span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">asyncio.</span></span><span class="sig-name descname"><span class="pre">TimerHandle</span></span><a class="headerlink" href="#asyncio.TimerHandle" title="Link to this definition">¶</a></dt>

  1689. <dd><p>A callback wrapper object returned by <a class="reference internal" href="#asyncio.loop.call_later" title="asyncio.loop.call_later"><code class="xref py py-meth docutils literal notranslate"><span class="pre">loop.call_later()</span></code></a>,

  1690. and <a class="reference internal" href="#asyncio.loop.call_at" title="asyncio.loop.call_at"><code class="xref py py-meth docutils literal notranslate"><span class="pre">loop.call_at()</span></code></a>.</p>

  1691. <p>This class is a subclass of <a class="reference internal" href="#asyncio.Handle" title="asyncio.Handle"><code class="xref py py-class docutils literal notranslate"><span class="pre">Handle</span></code></a>.</p>

  1692. <dl class="py method">

  1693. <dt class="sig sig-object py" id="asyncio.TimerHandle.when">

  1694. <span class="sig-name descname"><span class="pre">when</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.TimerHandle.when" title="Link to this definition">¶</a></dt>

  1695. <dd><p>Return a scheduled callback time as <a class="reference internal" href="functions.html#float" title="float"><code class="xref py py-class docutils literal notranslate"><span class="pre">float</span></code></a> seconds.</p>

  1696. <p>The time is an absolute timestamp, using the same time

  1697. reference as <a class="reference internal" href="#asyncio.loop.time" title="asyncio.loop.time"><code class="xref py py-meth docutils literal notranslate"><span class="pre">loop.time()</span></code></a>.</p>

  1698. <div class="versionadded">

  1699. <p><span class="versionmodified added">New in version 3.7.</span></p>

  1700. </div>

  1701. </dd></dl>

  1702. 

  1703. </dd></dl>

  1704. 

  1705. </section>

  1706. <section id="server-objects">

  1707. <h2>Server Objects<a class="headerlink" href="#server-objects" title="Link to this heading">¶</a></h2>

  1708. <p>Server objects are created by <a class="reference internal" href="#asyncio.loop.create_server" title="asyncio.loop.create_server"><code class="xref py py-meth docutils literal notranslate"><span class="pre">loop.create_server()</span></code></a>,

  1709. <a class="reference internal" href="#asyncio.loop.create_unix_server" title="asyncio.loop.create_unix_server"><code class="xref py py-meth docutils literal notranslate"><span class="pre">loop.create_unix_server()</span></code></a>, <a class="reference internal" href="asyncio-stream.html#asyncio.start_server" title="asyncio.start_server"><code class="xref py py-func docutils literal notranslate"><span class="pre">start_server()</span></code></a>,

  1710. and <a class="reference internal" href="asyncio-stream.html#asyncio.start_unix_server" title="asyncio.start_unix_server"><code class="xref py py-func docutils literal notranslate"><span class="pre">start_unix_server()</span></code></a> functions.</p>

  1711. <p>Do not instantiate the <a class="reference internal" href="#asyncio.Server" title="asyncio.Server"><code class="xref py py-class docutils literal notranslate"><span class="pre">Server</span></code></a> class directly.</p>

  1712. <dl class="py class">

  1713. <dt class="sig sig-object py" id="asyncio.Server">

  1714. <em class="property"><span class="pre">class</span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">asyncio.</span></span><span class="sig-name descname"><span class="pre">Server</span></span><a class="headerlink" href="#asyncio.Server" title="Link to this definition">¶</a></dt>

  1715. <dd><p><em>Server</em> objects are asynchronous context managers.  When used in an

  1716. <code class="docutils literal notranslate"><span class="pre">async</span> <span class="pre">with</span></code> statement, it’s guaranteed that the Server object is

  1717. closed and not accepting new connections when the <code class="docutils literal notranslate"><span class="pre">async</span> <span class="pre">with</span></code>

  1718. statement is completed:</p>

  1719. <div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="n">srv</span> <span class="o">=</span> <span class="k">await</span> <span class="n">loop</span><span class="o">.</span><span class="n">create_server</span><span class="p">(</span><span class="o">...</span><span class="p">)</span>

  1720. 

  1721. <span class="k">async</span> <span class="k">with</span> <span class="n">srv</span><span class="p">:</span>

  1722.     <span class="c1"># some code</span>

  1723. 

  1724. <span class="c1"># At this point, srv is closed and no longer accepts new connections.</span>

  1725. </pre></div>

  1726. </div>

  1727. <div class="versionchanged">

  1728. <p><span class="versionmodified changed">Changed in version 3.7: </span>Server object is an asynchronous context manager since Python 3.7.</p>

  1729. </div>

  1730. <div class="versionchanged">

  1731. <p><span class="versionmodified changed">Changed in version 3.11: </span>This class was exposed publicly as <code class="docutils literal notranslate"><span class="pre">asyncio.Server</span></code> in Python 3.9.11, 3.10.3 and 3.11.</p>

  1732. </div>

  1733. <dl class="py method">

  1734. <dt class="sig sig-object py" id="asyncio.Server.close">

  1735. <span class="sig-name descname"><span class="pre">close</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.Server.close" title="Link to this definition">¶</a></dt>

  1736. <dd><p>Stop serving: close listening sockets and set the <a class="reference internal" href="#asyncio.Server.sockets" title="asyncio.Server.sockets"><code class="xref py py-attr docutils literal notranslate"><span class="pre">sockets</span></code></a>

  1737. attribute to <code class="docutils literal notranslate"><span class="pre">None</span></code>.</p>

  1738. <p>The sockets that represent existing incoming client connections

  1739. are left open.</p>

  1740. <p>The server is closed asynchronously; use the <a class="reference internal" href="#asyncio.Server.wait_closed" title="asyncio.Server.wait_closed"><code class="xref py py-meth docutils literal notranslate"><span class="pre">wait_closed()</span></code></a>

  1741. coroutine to wait until the server is closed (and no more

  1742. connections are active).</p>

  1743. </dd></dl>

  1744. 

  1745. <dl class="py method">

  1746. <dt class="sig sig-object py" id="asyncio.Server.get_loop">

  1747. <span class="sig-name descname"><span class="pre">get_loop</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.Server.get_loop" title="Link to this definition">¶</a></dt>

  1748. <dd><p>Return the event loop associated with the server object.</p>

  1749. <div class="versionadded">

  1750. <p><span class="versionmodified added">New in version 3.7.</span></p>

  1751. </div>

  1752. </dd></dl>

  1753. 

  1754. <dl class="py method">

  1755. <dt class="sig sig-object py" id="asyncio.Server.start_serving">

  1756. <em class="property"><span class="pre">coroutine</span> </em><span class="sig-name descname"><span class="pre">start_serving</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.Server.start_serving" title="Link to this definition">¶</a></dt>

  1757. <dd><p>Start accepting connections.</p>

  1758. <p>This method is idempotent, so it can be called when

  1759. the server is already serving.</p>

  1760. <p>The <em>start_serving</em> keyword-only parameter to

  1761. <a class="reference internal" href="#asyncio.loop.create_server" title="asyncio.loop.create_server"><code class="xref py py-meth docutils literal notranslate"><span class="pre">loop.create_server()</span></code></a> and

  1762. <a class="reference internal" href="asyncio-stream.html#asyncio.start_server" title="asyncio.start_server"><code class="xref py py-meth docutils literal notranslate"><span class="pre">asyncio.start_server()</span></code></a> allows creating a Server object

  1763. that is not accepting connections initially.  In this case

  1764. <code class="docutils literal notranslate"><span class="pre">Server.start_serving()</span></code>, or <a class="reference internal" href="#asyncio.Server.serve_forever" title="asyncio.Server.serve_forever"><code class="xref py py-meth docutils literal notranslate"><span class="pre">Server.serve_forever()</span></code></a> can be used

  1765. to make the Server start accepting connections.</p>

  1766. <div class="versionadded">

  1767. <p><span class="versionmodified added">New in version 3.7.</span></p>

  1768. </div>

  1769. </dd></dl>

  1770. 

  1771. <dl class="py method">

  1772. <dt class="sig sig-object py" id="asyncio.Server.serve_forever">

  1773. <em class="property"><span class="pre">coroutine</span> </em><span class="sig-name descname"><span class="pre">serve_forever</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.Server.serve_forever" title="Link to this definition">¶</a></dt>

  1774. <dd><p>Start accepting connections until the coroutine is cancelled.

  1775. Cancellation of <code class="docutils literal notranslate"><span class="pre">serve_forever</span></code> task causes the server

  1776. to be closed.</p>

  1777. <p>This method can be called if the server is already accepting

  1778. connections.  Only one <code class="docutils literal notranslate"><span class="pre">serve_forever</span></code> task can exist per

  1779. one <em>Server</em> object.</p>

  1780. <p>Example:</p>

  1781. <div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="k">async</span> <span class="k">def</span> <span class="nf">client_connected</span><span class="p">(</span><span class="n">reader</span><span class="p">,</span> <span class="n">writer</span><span class="p">):</span>

  1782.     <span class="c1"># Communicate with the client with</span>

  1783.     <span class="c1"># reader/writer streams.  For example:</span>

  1784.     <span class="k">await</span> <span class="n">reader</span><span class="o">.</span><span class="n">readline</span><span class="p">()</span>

  1785. 

  1786. <span class="k">async</span> <span class="k">def</span> <span class="nf">main</span><span class="p">(</span><span class="n">host</span><span class="p">,</span> <span class="n">port</span><span class="p">):</span>

  1787.     <span class="n">srv</span> <span class="o">=</span> <span class="k">await</span> <span class="n">asyncio</span><span class="o">.</span><span class="n">start_server</span><span class="p">(</span>

  1788.         <span class="n">client_connected</span><span class="p">,</span> <span class="n">host</span><span class="p">,</span> <span class="n">port</span><span class="p">)</span>

  1789.     <span class="k">await</span> <span class="n">srv</span><span class="o">.</span><span class="n">serve_forever</span><span class="p">()</span>

  1790. 

  1791. <span class="n">asyncio</span><span class="o">.</span><span class="n">run</span><span class="p">(</span><span class="n">main</span><span class="p">(</span><span class="s1">&#39;127.0.0.1&#39;</span><span class="p">,</span> <span class="mi">0</span><span class="p">))</span>

  1792. </pre></div>

  1793. </div>

  1794. <div class="versionadded">

  1795. <p><span class="versionmodified added">New in version 3.7.</span></p>

  1796. </div>

  1797. </dd></dl>

  1798. 

  1799. <dl class="py method">

  1800. <dt class="sig sig-object py" id="asyncio.Server.is_serving">

  1801. <span class="sig-name descname"><span class="pre">is_serving</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.Server.is_serving" title="Link to this definition">¶</a></dt>

  1802. <dd><p>Return <code class="docutils literal notranslate"><span class="pre">True</span></code> if the server is accepting new connections.</p>

  1803. <div class="versionadded">

  1804. <p><span class="versionmodified added">New in version 3.7.</span></p>

  1805. </div>

  1806. </dd></dl>

  1807. 

  1808. <dl class="py method">

  1809. <dt class="sig sig-object py" id="asyncio.Server.wait_closed">

  1810. <em class="property"><span class="pre">coroutine</span> </em><span class="sig-name descname"><span class="pre">wait_closed</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.Server.wait_closed" title="Link to this definition">¶</a></dt>

  1811. <dd><p>Wait until the <a class="reference internal" href="#asyncio.Server.close" title="asyncio.Server.close"><code class="xref py py-meth docutils literal notranslate"><span class="pre">close()</span></code></a> method completes and all active

  1812. connections have finished.</p>

  1813. </dd></dl>

  1814. 

  1815. <dl class="py attribute">

  1816. <dt class="sig sig-object py" id="asyncio.Server.sockets">

  1817. <span class="sig-name descname"><span class="pre">sockets</span></span><a class="headerlink" href="#asyncio.Server.sockets" title="Link to this definition">¶</a></dt>

  1818. <dd><p>List of socket-like objects, <code class="docutils literal notranslate"><span class="pre">asyncio.trsock.TransportSocket</span></code>, which

  1819. the server is listening on.</p>

  1820. <div class="versionchanged">

  1821. <p><span class="versionmodified changed">Changed in version 3.7: </span>Prior to Python 3.7 <code class="docutils literal notranslate"><span class="pre">Server.sockets</span></code> used to return an

  1822. internal list of server sockets directly.  In 3.7 a copy

  1823. of that list is returned.</p>

  1824. </div>

  1825. </dd></dl>

  1826. 

  1827. </dd></dl>

  1828. 

  1829. </section>

  1830. <section id="event-loop-implementations">

  1831. <span id="asyncio-event-loop-implementations"></span><span id="asyncio-event-loops"></span><h2>Event Loop Implementations<a class="headerlink" href="#event-loop-implementations" title="Link to this heading">¶</a></h2>

  1832. <p>asyncio ships with two different event loop implementations:

  1833. <a class="reference internal" href="#asyncio.SelectorEventLoop" title="asyncio.SelectorEventLoop"><code class="xref py py-class docutils literal notranslate"><span class="pre">SelectorEventLoop</span></code></a> and <a class="reference internal" href="#asyncio.ProactorEventLoop" title="asyncio.ProactorEventLoop"><code class="xref py py-class docutils literal notranslate"><span class="pre">ProactorEventLoop</span></code></a>.</p>

  1834. <p>By default asyncio is configured to use <a class="reference internal" href="#asyncio.SelectorEventLoop" title="asyncio.SelectorEventLoop"><code class="xref py py-class docutils literal notranslate"><span class="pre">SelectorEventLoop</span></code></a>

  1835. on Unix and <a class="reference internal" href="#asyncio.ProactorEventLoop" title="asyncio.ProactorEventLoop"><code class="xref py py-class docutils literal notranslate"><span class="pre">ProactorEventLoop</span></code></a> on Windows.</p>

  1836. <dl class="py class">

  1837. <dt class="sig sig-object py" id="asyncio.SelectorEventLoop">

  1838. <em class="property"><span class="pre">class</span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">asyncio.</span></span><span class="sig-name descname"><span class="pre">SelectorEventLoop</span></span><a class="headerlink" href="#asyncio.SelectorEventLoop" title="Link to this definition">¶</a></dt>

  1839. <dd><p>An event loop based on the <a class="reference internal" href="selectors.html#module-selectors" title="selectors: High-level I/O multiplexing."><code class="xref py py-mod docutils literal notranslate"><span class="pre">selectors</span></code></a> module.</p>

  1840. <p>Uses the most efficient <em>selector</em> available for the given

  1841. platform.  It is also possible to manually configure the

  1842. exact selector implementation to be used:</p>

  1843. <div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="kn">import</span> <span class="nn">asyncio</span>

  1844. <span class="kn">import</span> <span class="nn">selectors</span>

  1845. 

  1846. <span class="k">class</span> <span class="nc">MyPolicy</span><span class="p">(</span><span class="n">asyncio</span><span class="o">.</span><span class="n">DefaultEventLoopPolicy</span><span class="p">):</span>

  1847.    <span class="k">def</span> <span class="nf">new_event_loop</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>

  1848.       <span class="n">selector</span> <span class="o">=</span> <span class="n">selectors</span><span class="o">.</span><span class="n">SelectSelector</span><span class="p">()</span>

  1849.       <span class="k">return</span> <span class="n">asyncio</span><span class="o">.</span><span class="n">SelectorEventLoop</span><span class="p">(</span><span class="n">selector</span><span class="p">)</span>

  1850. 

  1851. <span class="n">asyncio</span><span class="o">.</span><span class="n">set_event_loop_policy</span><span class="p">(</span><span class="n">MyPolicy</span><span class="p">())</span>

  1852. </pre></div>

  1853. </div>

  1854. <div class="availability docutils container">

  1855. <p><a class="reference internal" href="intro.html#availability"><span class="std std-ref">Availability</span></a>: Unix, Windows.</p>

  1856. </div>

  1857. </dd></dl>

  1858. 

  1859. <dl class="py class">

  1860. <dt class="sig sig-object py" id="asyncio.ProactorEventLoop">

  1861. <em class="property"><span class="pre">class</span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">asyncio.</span></span><span class="sig-name descname"><span class="pre">ProactorEventLoop</span></span><a class="headerlink" href="#asyncio.ProactorEventLoop" title="Link to this definition">¶</a></dt>

  1862. <dd><p>An event loop for Windows that uses “I/O Completion Ports” (IOCP).</p>

  1863. <div class="availability docutils container">

  1864. <p><a class="reference internal" href="intro.html#availability"><span class="std std-ref">Availability</span></a>: Windows.</p>

  1865. </div>

  1866. <div class="admonition seealso">

  1867. <p class="admonition-title">See also</p>

  1868. <p><a class="reference external" href="https://docs.microsoft.com/en-ca/windows/desktop/FileIO/i-o-completion-ports">MSDN documentation on I/O Completion Ports</a>.</p>

  1869. </div>

  1870. </dd></dl>

  1871. 

  1872. <dl class="py class">

  1873. <dt class="sig sig-object py" id="asyncio.AbstractEventLoop">

  1874. <em class="property"><span class="pre">class</span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">asyncio.</span></span><span class="sig-name descname"><span class="pre">AbstractEventLoop</span></span><a class="headerlink" href="#asyncio.AbstractEventLoop" title="Link to this definition">¶</a></dt>

  1875. <dd><p>Abstract base class for asyncio-compliant event loops.</p>

  1876. <p>The <a class="reference internal" href="#asyncio-event-loop-methods"><span class="std std-ref">Event Loop Methods</span></a> section lists all

  1877. methods that an alternative implementation of <code class="docutils literal notranslate"><span class="pre">AbstractEventLoop</span></code>

  1878. should have defined.</p>

  1879. </dd></dl>

  1880. 

  1881. </section>

  1882. <section id="examples">

  1883. <h2>Examples<a class="headerlink" href="#examples" title="Link to this heading">¶</a></h2>

  1884. <p>Note that all examples in this section <strong>purposefully</strong> show how

  1885. to use the low-level event loop APIs, such as <a class="reference internal" href="#asyncio.loop.run_forever" title="asyncio.loop.run_forever"><code class="xref py py-meth docutils literal notranslate"><span class="pre">loop.run_forever()</span></code></a>

  1886. and <a class="reference internal" href="#asyncio.loop.call_soon" title="asyncio.loop.call_soon"><code class="xref py py-meth docutils literal notranslate"><span class="pre">loop.call_soon()</span></code></a>.  Modern asyncio applications rarely

  1887. need to be written this way; consider using the high-level functions

  1888. like <a class="reference internal" href="asyncio-runner.html#asyncio.run" title="asyncio.run"><code class="xref py py-func docutils literal notranslate"><span class="pre">asyncio.run()</span></code></a>.</p>

  1889. <section id="hello-world-with-call-soon">

  1890. <span id="asyncio-example-lowlevel-helloworld"></span><h3>Hello World with call_soon()<a class="headerlink" href="#hello-world-with-call-soon" title="Link to this heading">¶</a></h3>

  1891. <p>An example using the <a class="reference internal" href="#asyncio.loop.call_soon" title="asyncio.loop.call_soon"><code class="xref py py-meth docutils literal notranslate"><span class="pre">loop.call_soon()</span></code></a> method to schedule a

  1892. callback. The callback displays <code class="docutils literal notranslate"><span class="pre">&quot;Hello</span> <span class="pre">World&quot;</span></code> and then stops the

  1893. event loop:</p>

  1894. <div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="kn">import</span> <span class="nn">asyncio</span>

  1895. 

  1896. <span class="k">def</span> <span class="nf">hello_world</span><span class="p">(</span><span class="n">loop</span><span class="p">):</span>

  1897. <span class="w">    </span><span class="sd">&quot;&quot;&quot;A callback to print &#39;Hello World&#39; and stop the event loop&quot;&quot;&quot;</span>

  1898.     <span class="nb">print</span><span class="p">(</span><span class="s1">&#39;Hello World&#39;</span><span class="p">)</span>

  1899.     <span class="n">loop</span><span class="o">.</span><span class="n">stop</span><span class="p">()</span>

  1900. 

  1901. <span class="n">loop</span> <span class="o">=</span> <span class="n">asyncio</span><span class="o">.</span><span class="n">new_event_loop</span><span class="p">()</span>

  1902. 

  1903. <span class="c1"># Schedule a call to hello_world()</span>

  1904. <span class="n">loop</span><span class="o">.</span><span class="n">call_soon</span><span class="p">(</span><span class="n">hello_world</span><span class="p">,</span> <span class="n">loop</span><span class="p">)</span>

  1905. 

  1906. <span class="c1"># Blocking call interrupted by loop.stop()</span>

  1907. <span class="k">try</span><span class="p">:</span>

  1908.     <span class="n">loop</span><span class="o">.</span><span class="n">run_forever</span><span class="p">()</span>

  1909. <span class="k">finally</span><span class="p">:</span>

  1910.     <span class="n">loop</span><span class="o">.</span><span class="n">close</span><span class="p">()</span>

  1911. </pre></div>

  1912. </div>

  1913. <div class="admonition seealso">

  1914. <p class="admonition-title">See also</p>

  1915. <p>A similar <a class="reference internal" href="asyncio-task.html#coroutine"><span class="std std-ref">Hello World</span></a>

  1916. example created with a coroutine and the <a class="reference internal" href="asyncio-runner.html#asyncio.run" title="asyncio.run"><code class="xref py py-func docutils literal notranslate"><span class="pre">run()</span></code></a> function.</p>

  1917. </div>

  1918. </section>

  1919. <section id="display-the-current-date-with-call-later">

  1920. <span id="asyncio-example-call-later"></span><h3>Display the current date with call_later()<a class="headerlink" href="#display-the-current-date-with-call-later" title="Link to this heading">¶</a></h3>

  1921. <p>An example of a callback displaying the current date every second. The

  1922. callback uses the <a class="reference internal" href="#asyncio.loop.call_later" title="asyncio.loop.call_later"><code class="xref py py-meth docutils literal notranslate"><span class="pre">loop.call_later()</span></code></a> method to reschedule itself

  1923. after 5 seconds, and then stops the event loop:</p>

  1924. <div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="kn">import</span> <span class="nn">asyncio</span>

  1925. <span class="kn">import</span> <span class="nn">datetime</span>

  1926. 

  1927. <span class="k">def</span> <span class="nf">display_date</span><span class="p">(</span><span class="n">end_time</span><span class="p">,</span> <span class="n">loop</span><span class="p">):</span>

  1928.     <span class="nb">print</span><span class="p">(</span><span class="n">datetime</span><span class="o">.</span><span class="n">datetime</span><span class="o">.</span><span class="n">now</span><span class="p">())</span>

  1929.     <span class="k">if</span> <span class="p">(</span><span class="n">loop</span><span class="o">.</span><span class="n">time</span><span class="p">()</span> <span class="o">+</span> <span class="mf">1.0</span><span class="p">)</span> <span class="o">&lt;</span> <span class="n">end_time</span><span class="p">:</span>

  1930.         <span class="n">loop</span><span class="o">.</span><span class="n">call_later</span><span class="p">(</span><span class="mi">1</span><span class="p">,</span> <span class="n">display_date</span><span class="p">,</span> <span class="n">end_time</span><span class="p">,</span> <span class="n">loop</span><span class="p">)</span>

  1931.     <span class="k">else</span><span class="p">:</span>

  1932.         <span class="n">loop</span><span class="o">.</span><span class="n">stop</span><span class="p">()</span>

  1933. 

  1934. <span class="n">loop</span> <span class="o">=</span> <span class="n">asyncio</span><span class="o">.</span><span class="n">new_event_loop</span><span class="p">()</span>

  1935. 

  1936. <span class="c1"># Schedule the first call to display_date()</span>

  1937. <span class="n">end_time</span> <span class="o">=</span> <span class="n">loop</span><span class="o">.</span><span class="n">time</span><span class="p">()</span> <span class="o">+</span> <span class="mf">5.0</span>

  1938. <span class="n">loop</span><span class="o">.</span><span class="n">call_soon</span><span class="p">(</span><span class="n">display_date</span><span class="p">,</span> <span class="n">end_time</span><span class="p">,</span> <span class="n">loop</span><span class="p">)</span>

  1939. 

  1940. <span class="c1"># Blocking call interrupted by loop.stop()</span>

  1941. <span class="k">try</span><span class="p">:</span>

  1942.     <span class="n">loop</span><span class="o">.</span><span class="n">run_forever</span><span class="p">()</span>

  1943. <span class="k">finally</span><span class="p">:</span>

  1944.     <span class="n">loop</span><span class="o">.</span><span class="n">close</span><span class="p">()</span>

  1945. </pre></div>

  1946. </div>

  1947. <div class="admonition seealso">

  1948. <p class="admonition-title">See also</p>

  1949. <p>A similar <a class="reference internal" href="asyncio-task.html#asyncio-example-sleep"><span class="std std-ref">current date</span></a> example

  1950. created with a coroutine and the <a class="reference internal" href="asyncio-runner.html#asyncio.run" title="asyncio.run"><code class="xref py py-func docutils literal notranslate"><span class="pre">run()</span></code></a> function.</p>

  1951. </div>

  1952. </section>

  1953. <section id="watch-a-file-descriptor-for-read-events">

  1954. <span id="asyncio-example-watch-fd"></span><h3>Watch a file descriptor for read events<a class="headerlink" href="#watch-a-file-descriptor-for-read-events" title="Link to this heading">¶</a></h3>

  1955. <p>Wait until a file descriptor received some data using the

  1956. <a class="reference internal" href="#asyncio.loop.add_reader" title="asyncio.loop.add_reader"><code class="xref py py-meth docutils literal notranslate"><span class="pre">loop.add_reader()</span></code></a> method and then close the event loop:</p>

  1957. <div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="kn">import</span> <span class="nn">asyncio</span>

  1958. <span class="kn">from</span> <span class="nn">socket</span> <span class="kn">import</span> <span class="n">socketpair</span>

  1959. 

  1960. <span class="c1"># Create a pair of connected file descriptors</span>

  1961. <span class="n">rsock</span><span class="p">,</span> <span class="n">wsock</span> <span class="o">=</span> <span class="n">socketpair</span><span class="p">()</span>

  1962. 

  1963. <span class="n">loop</span> <span class="o">=</span> <span class="n">asyncio</span><span class="o">.</span><span class="n">new_event_loop</span><span class="p">()</span>

  1964. 

  1965. <span class="k">def</span> <span class="nf">reader</span><span class="p">():</span>

  1966.     <span class="n">data</span> <span class="o">=</span> <span class="n">rsock</span><span class="o">.</span><span class="n">recv</span><span class="p">(</span><span class="mi">100</span><span class="p">)</span>

  1967.     <span class="nb">print</span><span class="p">(</span><span class="s2">&quot;Received:&quot;</span><span class="p">,</span> <span class="n">data</span><span class="o">.</span><span class="n">decode</span><span class="p">())</span>

  1968. 

  1969.     <span class="c1"># We are done: unregister the file descriptor</span>

  1970.     <span class="n">loop</span><span class="o">.</span><span class="n">remove_reader</span><span class="p">(</span><span class="n">rsock</span><span class="p">)</span>

  1971. 

  1972.     <span class="c1"># Stop the event loop</span>

  1973.     <span class="n">loop</span><span class="o">.</span><span class="n">stop</span><span class="p">()</span>

  1974. 

  1975. <span class="c1"># Register the file descriptor for read event</span>

  1976. <span class="n">loop</span><span class="o">.</span><span class="n">add_reader</span><span class="p">(</span><span class="n">rsock</span><span class="p">,</span> <span class="n">reader</span><span class="p">)</span>

  1977. 

  1978. <span class="c1"># Simulate the reception of data from the network</span>

  1979. <span class="n">loop</span><span class="o">.</span><span class="n">call_soon</span><span class="p">(</span><span class="n">wsock</span><span class="o">.</span><span class="n">send</span><span class="p">,</span> <span class="s1">&#39;abc&#39;</span><span class="o">.</span><span class="n">encode</span><span class="p">())</span>

  1980. 

  1981. <span class="k">try</span><span class="p">:</span>

  1982.     <span class="c1"># Run the event loop</span>

  1983.     <span class="n">loop</span><span class="o">.</span><span class="n">run_forever</span><span class="p">()</span>

  1984. <span class="k">finally</span><span class="p">:</span>

  1985.     <span class="c1"># We are done. Close sockets and the event loop.</span>

  1986.     <span class="n">rsock</span><span class="o">.</span><span class="n">close</span><span class="p">()</span>

  1987.     <span class="n">wsock</span><span class="o">.</span><span class="n">close</span><span class="p">()</span>

  1988.     <span class="n">loop</span><span class="o">.</span><span class="n">close</span><span class="p">()</span>

  1989. </pre></div>

  1990. </div>

  1991. <div class="admonition seealso">

  1992. <p class="admonition-title">See also</p>

  1993. <ul class="simple">

  1994. <li><p>A similar <a class="reference internal" href="asyncio-protocol.html#asyncio-example-create-connection"><span class="std std-ref">example</span></a>

  1995. using transports, protocols, and the

  1996. <a class="reference internal" href="#asyncio.loop.create_connection" title="asyncio.loop.create_connection"><code class="xref py py-meth docutils literal notranslate"><span class="pre">loop.create_connection()</span></code></a> method.</p></li>

  1997. <li><p>Another similar <a class="reference internal" href="asyncio-stream.html#asyncio-example-create-connection-streams"><span class="std std-ref">example</span></a>

  1998. using the high-level <a class="reference internal" href="asyncio-stream.html#asyncio.open_connection" title="asyncio.open_connection"><code class="xref py py-func docutils literal notranslate"><span class="pre">asyncio.open_connection()</span></code></a> function

  1999. and streams.</p></li>

  2000. </ul>

  2001. </div>

  2002. </section>

  2003. <section id="set-signal-handlers-for-sigint-and-sigterm">

  2004. <span id="asyncio-example-unix-signals"></span><h3>Set signal handlers for SIGINT and SIGTERM<a class="headerlink" href="#set-signal-handlers-for-sigint-and-sigterm" title="Link to this heading">¶</a></h3>

  2005. <p>(This <code class="docutils literal notranslate"><span class="pre">signals</span></code> example only works on Unix.)</p>

  2006. <p>Register handlers for signals <a class="reference internal" href="signal.html#signal.SIGINT" title="signal.SIGINT"><code class="xref py py-const docutils literal notranslate"><span class="pre">SIGINT</span></code></a> and <a class="reference internal" href="signal.html#signal.SIGTERM" title="signal.SIGTERM"><code class="xref py py-const docutils literal notranslate"><span class="pre">SIGTERM</span></code></a>

  2007. using the <a class="reference internal" href="#asyncio.loop.add_signal_handler" title="asyncio.loop.add_signal_handler"><code class="xref py py-meth docutils literal notranslate"><span class="pre">loop.add_signal_handler()</span></code></a> method:</p>

  2008. <div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="kn">import</span> <span class="nn">asyncio</span>

  2009. <span class="kn">import</span> <span class="nn">functools</span>

  2010. <span class="kn">import</span> <span class="nn">os</span>

  2011. <span class="kn">import</span> <span class="nn">signal</span>

  2012. 

  2013. <span class="k">def</span> <span class="nf">ask_exit</span><span class="p">(</span><span class="n">signame</span><span class="p">,</span> <span class="n">loop</span><span class="p">):</span>

  2014.     <span class="nb">print</span><span class="p">(</span><span class="s2">&quot;got signal </span><span class="si">%s</span><span class="s2">: exit&quot;</span> <span class="o">%</span> <span class="n">signame</span><span class="p">)</span>

  2015.     <span class="n">loop</span><span class="o">.</span><span class="n">stop</span><span class="p">()</span>

  2016. 

  2017. <span class="k">async</span> <span class="k">def</span> <span class="nf">main</span><span class="p">():</span>

  2018.     <span class="n">loop</span> <span class="o">=</span> <span class="n">asyncio</span><span class="o">.</span><span class="n">get_running_loop</span><span class="p">()</span>

  2019. 

  2020.     <span class="k">for</span> <span class="n">signame</span> <span class="ow">in</span> <span class="p">{</span><span class="s1">&#39;SIGINT&#39;</span><span class="p">,</span> <span class="s1">&#39;SIGTERM&#39;</span><span class="p">}:</span>

  2021.         <span class="n">loop</span><span class="o">.</span><span class="n">add_signal_handler</span><span class="p">(</span>

  2022.             <span class="nb">getattr</span><span class="p">(</span><span class="n">signal</span><span class="p">,</span> <span class="n">signame</span><span class="p">),</span>

  2023.             <span class="n">functools</span><span class="o">.</span><span class="n">partial</span><span class="p">(</span><span class="n">ask_exit</span><span class="p">,</span> <span class="n">signame</span><span class="p">,</span> <span class="n">loop</span><span class="p">))</span>

  2024. 

  2025.     <span class="k">await</span> <span class="n">asyncio</span><span class="o">.</span><span class="n">sleep</span><span class="p">(</span><span class="mi">3600</span><span class="p">)</span>

  2026. 

  2027. <span class="nb">print</span><span class="p">(</span><span class="s2">&quot;Event loop running for 1 hour, press Ctrl+C to interrupt.&quot;</span><span class="p">)</span>

  2028. <span class="nb">print</span><span class="p">(</span><span class="sa">f</span><span class="s2">&quot;pid </span><span class="si">{</span><span class="n">os</span><span class="o">.</span><span class="n">getpid</span><span class="p">()</span><span class="si">}</span><span class="s2">: send SIGINT or SIGTERM to exit.&quot;</span><span class="p">)</span>

  2029. 

  2030. <span class="n">asyncio</span><span class="o">.</span><span class="n">run</span><span class="p">(</span><span class="n">main</span><span class="p">())</span>

  2031. </pre></div>

  2032. </div>

  2033. </section>

  2034. </section>

  2035. </section>

  2036. 

  2037. 

  2038.             <div class="clearer"></div>

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  2042.       <div class="sphinxsidebar" role="navigation" aria-label="main navigation">

  2043.         <div class="sphinxsidebarwrapper">

  2044.   <div>

  2045.     <h3><a href="../contents.html">Table of Contents</a></h3>

  2046.     <ul>

  2047. <li><a class="reference internal" href="#">Event Loop</a><ul>

  2048. <li><a class="reference internal" href="#event-loop-methods">Event Loop Methods</a><ul>

  2049. <li><a class="reference internal" href="#running-and-stopping-the-loop">Running and stopping the loop</a></li>

  2050. <li><a class="reference internal" href="#scheduling-callbacks">Scheduling callbacks</a></li>

  2051. <li><a class="reference internal" href="#scheduling-delayed-callbacks">Scheduling delayed callbacks</a></li>

  2052. <li><a class="reference internal" href="#creating-futures-and-tasks">Creating Futures and Tasks</a></li>

  2053. <li><a class="reference internal" href="#opening-network-connections">Opening network connections</a></li>

  2054. <li><a class="reference internal" href="#creating-network-servers">Creating network servers</a></li>

  2055. <li><a class="reference internal" href="#transferring-files">Transferring files</a></li>

  2056. <li><a class="reference internal" href="#tls-upgrade">TLS Upgrade</a></li>

  2057. <li><a class="reference internal" href="#watching-file-descriptors">Watching file descriptors</a></li>

  2058. <li><a class="reference internal" href="#working-with-socket-objects-directly">Working with socket objects directly</a></li>

  2059. <li><a class="reference internal" href="#dns">DNS</a></li>

  2060. <li><a class="reference internal" href="#working-with-pipes">Working with pipes</a></li>

  2061. <li><a class="reference internal" href="#unix-signals">Unix signals</a></li>

  2062. <li><a class="reference internal" href="#executing-code-in-thread-or-process-pools">Executing code in thread or process pools</a></li>

  2063. <li><a class="reference internal" href="#error-handling-api">Error Handling API</a></li>

  2064. <li><a class="reference internal" href="#enabling-debug-mode">Enabling debug mode</a></li>

  2065. <li><a class="reference internal" href="#running-subprocesses">Running Subprocesses</a></li>

  2066. </ul>

  2067. </li>

  2068. <li><a class="reference internal" href="#callback-handles">Callback Handles</a></li>

  2069. <li><a class="reference internal" href="#server-objects">Server Objects</a></li>

  2070. <li><a class="reference internal" href="#event-loop-implementations">Event Loop Implementations</a></li>

  2071. <li><a class="reference internal" href="#examples">Examples</a><ul>

  2072. <li><a class="reference internal" href="#hello-world-with-call-soon">Hello World with call_soon()</a></li>

  2073. <li><a class="reference internal" href="#display-the-current-date-with-call-later">Display the current date with call_later()</a></li>

  2074. <li><a class="reference internal" href="#watch-a-file-descriptor-for-read-events">Watch a file descriptor for read events</a></li>

  2075. <li><a class="reference internal" href="#set-signal-handlers-for-sigint-and-sigterm">Set signal handlers for SIGINT and SIGTERM</a></li>

  2076. </ul>

  2077. </li>

  2078. </ul>

  2079. </li>

  2080. </ul>

  2081. 

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  2084.     <h4>Previous topic</h4>

  2085.     <p class="topless"><a href="asyncio-exceptions.html"

  2086.                           title="previous chapter">Exceptions</a></p>

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