400 lines
26 KiB
HTML
400 lines
26 KiB
HTML
|
|
|||
|
|
<!DOCTYPE html>
|
|||
|
|
|
|||
|
|
<html xmlns="http://www.w3.org/1999/xhtml">
|
|||
|
|
<head>
|
|||
|
|
<meta charset="utf-8" />
|
|||
|
|
<title>Queues — Python 3.7.4 documentation</title>
|
|||
|
|
<link rel="stylesheet" href="../_static/pydoctheme.css" type="text/css" />
|
|||
|
|
<link rel="stylesheet" href="../_static/pygments.css" type="text/css" />
|
|||
|
|
|
|||
|
|
<script type="text/javascript" id="documentation_options" data-url_root="../" src="../_static/documentation_options.js"></script>
|
|||
|
|
<script type="text/javascript" src="../_static/jquery.js"></script>
|
|||
|
|
<script type="text/javascript" src="../_static/underscore.js"></script>
|
|||
|
|
<script type="text/javascript" src="../_static/doctools.js"></script>
|
|||
|
|
<script type="text/javascript" src="../_static/language_data.js"></script>
|
|||
|
|
|
|||
|
|
<script type="text/javascript" src="../_static/sidebar.js"></script>
|
|||
|
|
|
|||
|
|
<link rel="search" type="application/opensearchdescription+xml"
|
|||
|
|
title="Search within Python 3.7.4 documentation"
|
|||
|
|
href="../_static/opensearch.xml"/>
|
|||
|
|
<link rel="author" title="About these documents" href="../about.html" />
|
|||
|
|
<link rel="index" title="Index" href="../genindex.html" />
|
|||
|
|
<link rel="search" title="Search" href="../search.html" />
|
|||
|
|
<link rel="copyright" title="Copyright" href="../copyright.html" />
|
|||
|
|
<link rel="next" title="Exceptions" href="asyncio-exceptions.html" />
|
|||
|
|
<link rel="prev" title="Subprocesses" href="asyncio-subprocess.html" />
|
|||
|
|
<link rel="shortcut icon" type="image/png" href="../_static/py.png" />
|
|||
|
|
<link rel="canonical" href="https://docs.python.org/3/library/asyncio-queue.html" />
|
|||
|
|
|
|||
|
|
<script type="text/javascript" src="../_static/copybutton.js"></script>
|
|||
|
|
<script type="text/javascript" src="../_static/switchers.js"></script>
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
<style>
|
|||
|
|
@media only screen {
|
|||
|
|
table.full-width-table {
|
|||
|
|
width: 100%;
|
|||
|
|
}
|
|||
|
|
}
|
|||
|
|
</style>
|
|||
|
|
|
|||
|
|
|
|||
|
|
</head><body>
|
|||
|
|
|
|||
|
|
<div class="related" role="navigation" aria-label="related navigation">
|
|||
|
|
<h3>Navigation</h3>
|
|||
|
|
<ul>
|
|||
|
|
<li class="right" style="margin-right: 10px">
|
|||
|
|
<a href="../genindex.html" title="General Index"
|
|||
|
|
accesskey="I">index</a></li>
|
|||
|
|
<li class="right" >
|
|||
|
|
<a href="../py-modindex.html" title="Python Module Index"
|
|||
|
|
>modules</a> |</li>
|
|||
|
|
<li class="right" >
|
|||
|
|
<a href="asyncio-exceptions.html" title="Exceptions"
|
|||
|
|
accesskey="N">next</a> |</li>
|
|||
|
|
<li class="right" >
|
|||
|
|
<a href="asyncio-subprocess.html" title="Subprocesses"
|
|||
|
|
accesskey="P">previous</a> |</li>
|
|||
|
|
<li><img src="../_static/py.png" alt=""
|
|||
|
|
style="vertical-align: middle; margin-top: -1px"/></li>
|
|||
|
|
<li><a href="https://www.python.org/">Python</a> »</li>
|
|||
|
|
<li>
|
|||
|
|
<span class="language_switcher_placeholder">en</span>
|
|||
|
|
<span class="version_switcher_placeholder">3.7.4</span>
|
|||
|
|
<a href="../index.html">Documentation </a> »
|
|||
|
|
</li>
|
|||
|
|
|
|||
|
|
<li class="nav-item nav-item-1"><a href="index.html" >The Python Standard Library</a> »</li>
|
|||
|
|
<li class="nav-item nav-item-2"><a href="ipc.html" >Networking and Interprocess Communication</a> »</li>
|
|||
|
|
<li class="nav-item nav-item-3"><a href="asyncio.html" accesskey="U"><code class="xref py py-mod docutils literal notranslate"><span class="pre">asyncio</span></code> — Asynchronous I/O</a> »</li>
|
|||
|
|
<li class="right">
|
|||
|
|
|
|||
|
|
|
|||
|
|
<div class="inline-search" style="display: none" role="search">
|
|||
|
|
<form class="inline-search" action="../search.html" method="get">
|
|||
|
|
<input placeholder="Quick search" type="text" name="q" />
|
|||
|
|
<input type="submit" value="Go" />
|
|||
|
|
<input type="hidden" name="check_keywords" value="yes" />
|
|||
|
|
<input type="hidden" name="area" value="default" />
|
|||
|
|
</form>
|
|||
|
|
</div>
|
|||
|
|
<script type="text/javascript">$('.inline-search').show(0);</script>
|
|||
|
|
|
|
|||
|
|
</li>
|
|||
|
|
|
|||
|
|
</ul>
|
|||
|
|
</div>
|
|||
|
|
|
|||
|
|
<div class="document">
|
|||
|
|
<div class="documentwrapper">
|
|||
|
|
<div class="bodywrapper">
|
|||
|
|
<div class="body" role="main">
|
|||
|
|
|
|||
|
|
<div class="section" id="queues">
|
|||
|
|
<span id="asyncio-queues"></span><h1>Queues<a class="headerlink" href="#queues" title="Permalink to this headline">¶</a></h1>
|
|||
|
|
<p>asyncio queues are designed to be similar to classes of the
|
|||
|
|
<a class="reference internal" href="queue.html#module-queue" title="queue: A synchronized queue class."><code class="xref py py-mod docutils literal notranslate"><span class="pre">queue</span></code></a> module. Although asyncio queues are not thread-safe,
|
|||
|
|
they are designed to be used specifically in async/await code.</p>
|
|||
|
|
<p>Note that methods of asyncio queues don’t have a <em>timeout</em> parameter;
|
|||
|
|
use <a class="reference internal" href="asyncio-task.html#asyncio.wait_for" title="asyncio.wait_for"><code class="xref py py-func docutils literal notranslate"><span class="pre">asyncio.wait_for()</span></code></a> function to do queue operations with a
|
|||
|
|
timeout.</p>
|
|||
|
|
<p>See also the <a class="reference internal" href="#examples">Examples</a> section below.</p>
|
|||
|
|
<div class="section" id="queue">
|
|||
|
|
<h2>Queue<a class="headerlink" href="#queue" title="Permalink to this headline">¶</a></h2>
|
|||
|
|
<dl class="class">
|
|||
|
|
<dt id="asyncio.Queue">
|
|||
|
|
<em class="property">class </em><code class="descclassname">asyncio.</code><code class="descname">Queue</code><span class="sig-paren">(</span><em>maxsize=0</em>, <em>*</em>, <em>loop=None</em><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.Queue" title="Permalink to this definition">¶</a></dt>
|
|||
|
|
<dd><p>A first in, first out (FIFO) queue.</p>
|
|||
|
|
<p>If <em>maxsize</em> is less than or equal to zero, the queue size is
|
|||
|
|
infinite. If it is an integer greater than <code class="docutils literal notranslate"><span class="pre">0</span></code>, then
|
|||
|
|
<code class="docutils literal notranslate"><span class="pre">await</span> <span class="pre">put()</span></code> blocks when the queue reaches <em>maxsize</em>
|
|||
|
|
until an item is removed by <a class="reference internal" href="#asyncio.Queue.get" title="asyncio.Queue.get"><code class="xref py py-meth docutils literal notranslate"><span class="pre">get()</span></code></a>.</p>
|
|||
|
|
<p>Unlike the standard library threading <a class="reference internal" href="queue.html#module-queue" title="queue: A synchronized queue class."><code class="xref py py-mod docutils literal notranslate"><span class="pre">queue</span></code></a>, the size of
|
|||
|
|
the queue is always known and can be returned by calling the
|
|||
|
|
<a class="reference internal" href="#asyncio.Queue.qsize" title="asyncio.Queue.qsize"><code class="xref py py-meth docutils literal notranslate"><span class="pre">qsize()</span></code></a> method.</p>
|
|||
|
|
<p>This class is <a class="reference internal" href="asyncio-dev.html#asyncio-multithreading"><span class="std std-ref">not thread safe</span></a>.</p>
|
|||
|
|
<dl class="attribute">
|
|||
|
|
<dt id="asyncio.Queue.maxsize">
|
|||
|
|
<code class="descname">maxsize</code><a class="headerlink" href="#asyncio.Queue.maxsize" title="Permalink to this definition">¶</a></dt>
|
|||
|
|
<dd><p>Number of items allowed in the queue.</p>
|
|||
|
|
</dd></dl>
|
|||
|
|
|
|||
|
|
<dl class="method">
|
|||
|
|
<dt id="asyncio.Queue.empty">
|
|||
|
|
<code class="descname">empty</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.Queue.empty" title="Permalink to this definition">¶</a></dt>
|
|||
|
|
<dd><p>Return <code class="docutils literal notranslate"><span class="pre">True</span></code> if the queue is empty, <code class="docutils literal notranslate"><span class="pre">False</span></code> otherwise.</p>
|
|||
|
|
</dd></dl>
|
|||
|
|
|
|||
|
|
<dl class="method">
|
|||
|
|
<dt id="asyncio.Queue.full">
|
|||
|
|
<code class="descname">full</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.Queue.full" title="Permalink to this definition">¶</a></dt>
|
|||
|
|
<dd><p>Return <code class="docutils literal notranslate"><span class="pre">True</span></code> if there are <a class="reference internal" href="#asyncio.Queue.maxsize" title="asyncio.Queue.maxsize"><code class="xref py py-attr docutils literal notranslate"><span class="pre">maxsize</span></code></a> items in the queue.</p>
|
|||
|
|
<p>If the queue was initialized with <code class="docutils literal notranslate"><span class="pre">maxsize=0</span></code> (the default),
|
|||
|
|
then <a class="reference internal" href="#asyncio.Queue.full" title="asyncio.Queue.full"><code class="xref py py-meth docutils literal notranslate"><span class="pre">full()</span></code></a> never returns <code class="docutils literal notranslate"><span class="pre">True</span></code>.</p>
|
|||
|
|
</dd></dl>
|
|||
|
|
|
|||
|
|
<dl class="method">
|
|||
|
|
<dt id="asyncio.Queue.get">
|
|||
|
|
<em class="property">coroutine </em><code class="descname">get</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.Queue.get" title="Permalink to this definition">¶</a></dt>
|
|||
|
|
<dd><p>Remove and return an item from the queue. If queue is empty,
|
|||
|
|
wait until an item is available.</p>
|
|||
|
|
</dd></dl>
|
|||
|
|
|
|||
|
|
<dl class="method">
|
|||
|
|
<dt id="asyncio.Queue.get_nowait">
|
|||
|
|
<code class="descname">get_nowait</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.Queue.get_nowait" title="Permalink to this definition">¶</a></dt>
|
|||
|
|
<dd><p>Return an item if one is immediately available, else raise
|
|||
|
|
<a class="reference internal" href="#asyncio.QueueEmpty" title="asyncio.QueueEmpty"><code class="xref py py-exc docutils literal notranslate"><span class="pre">QueueEmpty</span></code></a>.</p>
|
|||
|
|
</dd></dl>
|
|||
|
|
|
|||
|
|
<dl class="method">
|
|||
|
|
<dt id="asyncio.Queue.join">
|
|||
|
|
<em class="property">coroutine </em><code class="descname">join</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.Queue.join" title="Permalink to this definition">¶</a></dt>
|
|||
|
|
<dd><p>Block until all items in the queue have been received and processed.</p>
|
|||
|
|
<p>The count of unfinished tasks goes up whenever an item is added
|
|||
|
|
to the queue. The count goes down whenever a consumer coroutine calls
|
|||
|
|
<a class="reference internal" href="#asyncio.Queue.task_done" title="asyncio.Queue.task_done"><code class="xref py py-meth docutils literal notranslate"><span class="pre">task_done()</span></code></a> to indicate that the item was retrieved and all
|
|||
|
|
work on it is complete. When the count of unfinished tasks drops
|
|||
|
|
to zero, <a class="reference internal" href="#asyncio.Queue.join" title="asyncio.Queue.join"><code class="xref py py-meth docutils literal notranslate"><span class="pre">join()</span></code></a> unblocks.</p>
|
|||
|
|
</dd></dl>
|
|||
|
|
|
|||
|
|
<dl class="method">
|
|||
|
|
<dt id="asyncio.Queue.put">
|
|||
|
|
<em class="property">coroutine </em><code class="descname">put</code><span class="sig-paren">(</span><em>item</em><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.Queue.put" title="Permalink to this definition">¶</a></dt>
|
|||
|
|
<dd><p>Put an item into the queue. If the queue is full, wait until a
|
|||
|
|
free slot is available before adding the item.</p>
|
|||
|
|
</dd></dl>
|
|||
|
|
|
|||
|
|
<dl class="method">
|
|||
|
|
<dt id="asyncio.Queue.put_nowait">
|
|||
|
|
<code class="descname">put_nowait</code><span class="sig-paren">(</span><em>item</em><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.Queue.put_nowait" title="Permalink to this definition">¶</a></dt>
|
|||
|
|
<dd><p>Put an item into the queue without blocking.</p>
|
|||
|
|
<p>If no free slot is immediately available, raise <a class="reference internal" href="#asyncio.QueueFull" title="asyncio.QueueFull"><code class="xref py py-exc docutils literal notranslate"><span class="pre">QueueFull</span></code></a>.</p>
|
|||
|
|
</dd></dl>
|
|||
|
|
|
|||
|
|
<dl class="method">
|
|||
|
|
<dt id="asyncio.Queue.qsize">
|
|||
|
|
<code class="descname">qsize</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.Queue.qsize" title="Permalink to this definition">¶</a></dt>
|
|||
|
|
<dd><p>Return the number of items in the queue.</p>
|
|||
|
|
</dd></dl>
|
|||
|
|
|
|||
|
|
<dl class="method">
|
|||
|
|
<dt id="asyncio.Queue.task_done">
|
|||
|
|
<code class="descname">task_done</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.Queue.task_done" title="Permalink to this definition">¶</a></dt>
|
|||
|
|
<dd><p>Indicate that a formerly enqueued task is complete.</p>
|
|||
|
|
<p>Used by queue consumers. For each <a class="reference internal" href="#asyncio.Queue.get" title="asyncio.Queue.get"><code class="xref py py-meth docutils literal notranslate"><span class="pre">get()</span></code></a> used to
|
|||
|
|
fetch a task, a subsequent call to <a class="reference internal" href="#asyncio.Queue.task_done" title="asyncio.Queue.task_done"><code class="xref py py-meth docutils literal notranslate"><span class="pre">task_done()</span></code></a> tells the
|
|||
|
|
queue that the processing on the task is complete.</p>
|
|||
|
|
<p>If a <a class="reference internal" href="#asyncio.Queue.join" title="asyncio.Queue.join"><code class="xref py py-meth docutils literal notranslate"><span class="pre">join()</span></code></a> is currently blocking, it will resume when all
|
|||
|
|
items have been processed (meaning that a <a class="reference internal" href="#asyncio.Queue.task_done" title="asyncio.Queue.task_done"><code class="xref py py-meth docutils literal notranslate"><span class="pre">task_done()</span></code></a>
|
|||
|
|
call was received for every item that had been <a class="reference internal" href="#asyncio.Queue.put" title="asyncio.Queue.put"><code class="xref py py-meth docutils literal notranslate"><span class="pre">put()</span></code></a>
|
|||
|
|
into the queue).</p>
|
|||
|
|
<p>Raises <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 called more times than there were
|
|||
|
|
items placed in the queue.</p>
|
|||
|
|
</dd></dl>
|
|||
|
|
|
|||
|
|
</dd></dl>
|
|||
|
|
|
|||
|
|
</div>
|
|||
|
|
<div class="section" id="priority-queue">
|
|||
|
|
<h2>Priority Queue<a class="headerlink" href="#priority-queue" title="Permalink to this headline">¶</a></h2>
|
|||
|
|
<dl class="class">
|
|||
|
|
<dt id="asyncio.PriorityQueue">
|
|||
|
|
<em class="property">class </em><code class="descclassname">asyncio.</code><code class="descname">PriorityQueue</code><a class="headerlink" href="#asyncio.PriorityQueue" title="Permalink to this definition">¶</a></dt>
|
|||
|
|
<dd><p>A variant of <a class="reference internal" href="#asyncio.Queue" title="asyncio.Queue"><code class="xref py py-class docutils literal notranslate"><span class="pre">Queue</span></code></a>; retrieves entries in priority order
|
|||
|
|
(lowest first).</p>
|
|||
|
|
<p>Entries are typically tuples of the form
|
|||
|
|
<code class="docutils literal notranslate"><span class="pre">(priority_number,</span> <span class="pre">data)</span></code>.</p>
|
|||
|
|
</dd></dl>
|
|||
|
|
|
|||
|
|
</div>
|
|||
|
|
<div class="section" id="lifo-queue">
|
|||
|
|
<h2>LIFO Queue<a class="headerlink" href="#lifo-queue" title="Permalink to this headline">¶</a></h2>
|
|||
|
|
<dl class="class">
|
|||
|
|
<dt id="asyncio.LifoQueue">
|
|||
|
|
<em class="property">class </em><code class="descclassname">asyncio.</code><code class="descname">LifoQueue</code><a class="headerlink" href="#asyncio.LifoQueue" title="Permalink to this definition">¶</a></dt>
|
|||
|
|
<dd><p>A variant of <a class="reference internal" href="#asyncio.Queue" title="asyncio.Queue"><code class="xref py py-class docutils literal notranslate"><span class="pre">Queue</span></code></a> that retrieves most recently added
|
|||
|
|
entries first (last in, first out).</p>
|
|||
|
|
</dd></dl>
|
|||
|
|
|
|||
|
|
</div>
|
|||
|
|
<div class="section" id="exceptions">
|
|||
|
|
<h2>Exceptions<a class="headerlink" href="#exceptions" title="Permalink to this headline">¶</a></h2>
|
|||
|
|
<dl class="exception">
|
|||
|
|
<dt id="asyncio.QueueEmpty">
|
|||
|
|
<em class="property">exception </em><code class="descclassname">asyncio.</code><code class="descname">QueueEmpty</code><a class="headerlink" href="#asyncio.QueueEmpty" title="Permalink to this definition">¶</a></dt>
|
|||
|
|
<dd><p>This exception is raised when the <a class="reference internal" href="#asyncio.Queue.get_nowait" title="asyncio.Queue.get_nowait"><code class="xref py py-meth docutils literal notranslate"><span class="pre">get_nowait()</span></code></a> method
|
|||
|
|
is called on an empty queue.</p>
|
|||
|
|
</dd></dl>
|
|||
|
|
|
|||
|
|
<dl class="exception">
|
|||
|
|
<dt id="asyncio.QueueFull">
|
|||
|
|
<em class="property">exception </em><code class="descclassname">asyncio.</code><code class="descname">QueueFull</code><a class="headerlink" href="#asyncio.QueueFull" title="Permalink to this definition">¶</a></dt>
|
|||
|
|
<dd><p>Exception raised when the <a class="reference internal" href="#asyncio.Queue.put_nowait" title="asyncio.Queue.put_nowait"><code class="xref py py-meth docutils literal notranslate"><span class="pre">put_nowait()</span></code></a> method is called
|
|||
|
|
on a queue that has reached its <em>maxsize</em>.</p>
|
|||
|
|
</dd></dl>
|
|||
|
|
|
|||
|
|
</div>
|
|||
|
|
<div class="section" id="examples">
|
|||
|
|
<h2>Examples<a class="headerlink" href="#examples" title="Permalink to this headline">¶</a></h2>
|
|||
|
|
<p id="asyncio-example-queue-dist">Queues can be used to distribute workload between several
|
|||
|
|
concurrent tasks:</p>
|
|||
|
|
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="kn">import</span> <span class="nn">asyncio</span>
|
|||
|
|
<span class="kn">import</span> <span class="nn">random</span>
|
|||
|
|
<span class="kn">import</span> <span class="nn">time</span>
|
|||
|
|
|
|||
|
|
|
|||
|
|
<span class="k">async</span> <span class="k">def</span> <span class="nf">worker</span><span class="p">(</span><span class="n">name</span><span class="p">,</span> <span class="n">queue</span><span class="p">):</span>
|
|||
|
|
<span class="k">while</span> <span class="kc">True</span><span class="p">:</span>
|
|||
|
|
<span class="c1"># Get a "work item" out of the queue.</span>
|
|||
|
|
<span class="n">sleep_for</span> <span class="o">=</span> <span class="k">await</span> <span class="n">queue</span><span class="o">.</span><span class="n">get</span><span class="p">()</span>
|
|||
|
|
|
|||
|
|
<span class="c1"># Sleep for the "sleep_for" seconds.</span>
|
|||
|
|
<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="n">sleep_for</span><span class="p">)</span>
|
|||
|
|
|
|||
|
|
<span class="c1"># Notify the queue that the "work item" has been processed.</span>
|
|||
|
|
<span class="n">queue</span><span class="o">.</span><span class="n">task_done</span><span class="p">()</span>
|
|||
|
|
|
|||
|
|
<span class="nb">print</span><span class="p">(</span><span class="n">f</span><span class="s1">'</span><span class="si">{name}</span><span class="s1"> has slept for </span><span class="si">{sleep_for:.2f}</span><span class="s1"> seconds'</span><span class="p">)</span>
|
|||
|
|
|
|||
|
|
|
|||
|
|
<span class="k">async</span> <span class="k">def</span> <span class="nf">main</span><span class="p">():</span>
|
|||
|
|
<span class="c1"># Create a queue that we will use to store our "workload".</span>
|
|||
|
|
<span class="n">queue</span> <span class="o">=</span> <span class="n">asyncio</span><span class="o">.</span><span class="n">Queue</span><span class="p">()</span>
|
|||
|
|
|
|||
|
|
<span class="c1"># Generate random timings and put them into the queue.</span>
|
|||
|
|
<span class="n">total_sleep_time</span> <span class="o">=</span> <span class="mi">0</span>
|
|||
|
|
<span class="k">for</span> <span class="n">_</span> <span class="ow">in</span> <span class="nb">range</span><span class="p">(</span><span class="mi">20</span><span class="p">):</span>
|
|||
|
|
<span class="n">sleep_for</span> <span class="o">=</span> <span class="n">random</span><span class="o">.</span><span class="n">uniform</span><span class="p">(</span><span class="mf">0.05</span><span class="p">,</span> <span class="mf">1.0</span><span class="p">)</span>
|
|||
|
|
<span class="n">total_sleep_time</span> <span class="o">+=</span> <span class="n">sleep_for</span>
|
|||
|
|
<span class="n">queue</span><span class="o">.</span><span class="n">put_nowait</span><span class="p">(</span><span class="n">sleep_for</span><span class="p">)</span>
|
|||
|
|
|
|||
|
|
<span class="c1"># Create three worker tasks to process the queue concurrently.</span>
|
|||
|
|
<span class="n">tasks</span> <span class="o">=</span> <span class="p">[]</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">3</span><span class="p">):</span>
|
|||
|
|
<span class="n">task</span> <span class="o">=</span> <span class="n">asyncio</span><span class="o">.</span><span class="n">create_task</span><span class="p">(</span><span class="n">worker</span><span class="p">(</span><span class="n">f</span><span class="s1">'worker-</span><span class="si">{i}</span><span class="s1">'</span><span class="p">,</span> <span class="n">queue</span><span class="p">))</span>
|
|||
|
|
<span class="n">tasks</span><span class="o">.</span><span class="n">append</span><span class="p">(</span><span class="n">task</span><span class="p">)</span>
|
|||
|
|
|
|||
|
|
<span class="c1"># Wait until the queue is fully processed.</span>
|
|||
|
|
<span class="n">started_at</span> <span class="o">=</span> <span class="n">time</span><span class="o">.</span><span class="n">monotonic</span><span class="p">()</span>
|
|||
|
|
<span class="k">await</span> <span class="n">queue</span><span class="o">.</span><span class="n">join</span><span class="p">()</span>
|
|||
|
|
<span class="n">total_slept_for</span> <span class="o">=</span> <span class="n">time</span><span class="o">.</span><span class="n">monotonic</span><span class="p">()</span> <span class="o">-</span> <span class="n">started_at</span>
|
|||
|
|
|
|||
|
|
<span class="c1"># Cancel our worker tasks.</span>
|
|||
|
|
<span class="k">for</span> <span class="n">task</span> <span class="ow">in</span> <span class="n">tasks</span><span class="p">:</span>
|
|||
|
|
<span class="n">task</span><span class="o">.</span><span class="n">cancel</span><span class="p">()</span>
|
|||
|
|
<span class="c1"># Wait until all worker tasks are cancelled.</span>
|
|||
|
|
<span class="k">await</span> <span class="n">asyncio</span><span class="o">.</span><span class="n">gather</span><span class="p">(</span><span class="o">*</span><span class="n">tasks</span><span class="p">,</span> <span class="n">return_exceptions</span><span class="o">=</span><span class="kc">True</span><span class="p">)</span>
|
|||
|
|
|
|||
|
|
<span class="nb">print</span><span class="p">(</span><span class="s1">'===='</span><span class="p">)</span>
|
|||
|
|
<span class="nb">print</span><span class="p">(</span><span class="n">f</span><span class="s1">'3 workers slept in parallel for </span><span class="si">{total_slept_for:.2f}</span><span class="s1"> seconds'</span><span class="p">)</span>
|
|||
|
|
<span class="nb">print</span><span class="p">(</span><span class="n">f</span><span class="s1">'total expected sleep time: </span><span class="si">{total_sleep_time:.2f}</span><span class="s1"> seconds'</span><span class="p">)</span>
|
|||
|
|
|
|||
|
|
|
|||
|
|
<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>
|
|||
|
|
</pre></div>
|
|||
|
|
</div>
|
|||
|
|
</div>
|
|||
|
|
</div>
|
|||
|
|
|
|||
|
|
|
|||
|
|
</div>
|
|||
|
|
</div>
|
|||
|
|
</div>
|
|||
|
|
<div class="sphinxsidebar" role="navigation" aria-label="main navigation">
|
|||
|
|
<div class="sphinxsidebarwrapper">
|
|||
|
|
<h3><a href="../contents.html">Table of Contents</a></h3>
|
|||
|
|
<ul>
|
|||
|
|
<li><a class="reference internal" href="#">Queues</a><ul>
|
|||
|
|
<li><a class="reference internal" href="#queue">Queue</a></li>
|
|||
|
|
<li><a class="reference internal" href="#priority-queue">Priority Queue</a></li>
|
|||
|
|
<li><a class="reference internal" href="#lifo-queue">LIFO Queue</a></li>
|
|||
|
|
<li><a class="reference internal" href="#exceptions">Exceptions</a></li>
|
|||
|
|
<li><a class="reference internal" href="#examples">Examples</a></li>
|
|||
|
|
</ul>
|
|||
|
|
</li>
|
|||
|
|
</ul>
|
|||
|
|
|
|||
|
|
<h4>Previous topic</h4>
|
|||
|
|
<p class="topless"><a href="asyncio-subprocess.html"
|
|||
|
|
title="previous chapter">Subprocesses</a></p>
|
|||
|
|
<h4>Next topic</h4>
|
|||
|
|
<p class="topless"><a href="asyncio-exceptions.html"
|
|||
|
|
title="next chapter">Exceptions</a></p>
|
|||
|
|
<div role="note" aria-label="source link">
|
|||
|
|
<h3>This Page</h3>
|
|||
|
|
<ul class="this-page-menu">
|
|||
|
|
<li><a href="../bugs.html">Report a Bug</a></li>
|
|||
|
|
<li>
|
|||
|
|
<a href="https://github.com/python/cpython/blob/3.7/Doc/library/asyncio-queue.rst"
|
|||
|
|
rel="nofollow">Show Source
|
|||
|
|
</a>
|
|||
|
|
</li>
|
|||
|
|
</ul>
|
|||
|
|
</div>
|
|||
|
|
</div>
|
|||
|
|
</div>
|
|||
|
|
<div class="clearer"></div>
|
|||
|
|
</div>
|
|||
|
|
<div class="related" role="navigation" aria-label="related navigation">
|
|||
|
|
<h3>Navigation</h3>
|
|||
|
|
<ul>
|
|||
|
|
<li class="right" style="margin-right: 10px">
|
|||
|
|
<a href="../genindex.html" title="General Index"
|
|||
|
|
>index</a></li>
|
|||
|
|
<li class="right" >
|
|||
|
|
<a href="../py-modindex.html" title="Python Module Index"
|
|||
|
|
>modules</a> |</li>
|
|||
|
|
<li class="right" >
|
|||
|
|
<a href="asyncio-exceptions.html" title="Exceptions"
|
|||
|
|
>next</a> |</li>
|
|||
|
|
<li class="right" >
|
|||
|
|
<a href="asyncio-subprocess.html" title="Subprocesses"
|
|||
|
|
>previous</a> |</li>
|
|||
|
|
<li><img src="../_static/py.png" alt=""
|
|||
|
|
style="vertical-align: middle; margin-top: -1px"/></li>
|
|||
|
|
<li><a href="https://www.python.org/">Python</a> »</li>
|
|||
|
|
<li>
|
|||
|
|
<span class="language_switcher_placeholder">en</span>
|
|||
|
|
<span class="version_switcher_placeholder">3.7.4</span>
|
|||
|
|
<a href="../index.html">Documentation </a> »
|
|||
|
|
</li>
|
|||
|
|
|
|||
|
|
<li class="nav-item nav-item-1"><a href="index.html" >The Python Standard Library</a> »</li>
|
|||
|
|
<li class="nav-item nav-item-2"><a href="ipc.html" >Networking and Interprocess Communication</a> »</li>
|
|||
|
|
<li class="nav-item nav-item-3"><a href="asyncio.html" ><code class="xref py py-mod docutils literal notranslate"><span class="pre">asyncio</span></code> — Asynchronous I/O</a> »</li>
|
|||
|
|
<li class="right">
|
|||
|
|
|
|||
|
|
|
|||
|
|
<div class="inline-search" style="display: none" role="search">
|
|||
|
|
<form class="inline-search" action="../search.html" method="get">
|
|||
|
|
<input placeholder="Quick search" type="text" name="q" />
|
|||
|
|
<input type="submit" value="Go" />
|
|||
|
|
<input type="hidden" name="check_keywords" value="yes" />
|
|||
|
|
<input type="hidden" name="area" value="default" />
|
|||
|
|
</form>
|
|||
|
|
</div>
|
|||
|
|
<script type="text/javascript">$('.inline-search').show(0);</script>
|
|||
|
|
|
|
|||
|
|
</li>
|
|||
|
|
|
|||
|
|
</ul>
|
|||
|
|
</div>
|
|||
|
|
<div class="footer">
|
|||
|
|
© <a href="../copyright.html">Copyright</a> 2001-2019, Python Software Foundation.
|
|||
|
|
<br />
|
|||
|
|
The Python Software Foundation is a non-profit corporation.
|
|||
|
|
<a href="https://www.python.org/psf/donations/">Please donate.</a>
|
|||
|
|
<br />
|
|||
|
|
Last updated on Jul 13, 2019.
|
|||
|
|
<a href="../bugs.html">Found a bug</a>?
|
|||
|
|
<br />
|
|||
|
|
Created using <a href="http://sphinx.pocoo.org/">Sphinx</a> 2.0.1.
|
|||
|
|
</div>
|
|||
|
|
|
|||
|
|
</body>
|
|||
|
|
</html>
|