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<li><a class="reference internal" href="#">Call Graph Introspection</a><ul>
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  <section id="call-graph-introspection">
<span id="asyncio-graph"></span><h1>Call Graph Introspection<a class="headerlink" href="#call-graph-introspection" title="Link to this heading">¶</a></h1>
<p><strong>Source code:</strong> <a class="extlink-source reference external" href="https://github.com/python/cpython/tree/main/Lib/asyncio/graph.py">Lib/asyncio/graph.py</a></p>
<hr class="docutils" />
<p>asyncio has powerful runtime call graph introspection utilities
to trace the entire call graph of a running <em>coroutine</em> or <em>task</em>, or
a suspended <em>future</em>.  These utilities and the underlying machinery
can be used from within a Python program or by external profilers
and debuggers.</p>
<div class="versionadded">
<p><span class="versionmodified added">Added in version 3.14.</span></p>
</div>
<dl class="py function">
<dt class="sig sig-object py" id="asyncio.print_call_graph">
<span class="sig-prename descclassname"><span class="pre">asyncio.</span></span><span class="sig-name descname"><span class="pre">print_call_graph</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">future</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="positional-only-separator o"><abbr title="Positional-only parameter separator (PEP 570)"><span class="pre">/</span></abbr></span></em>, <em class="sig-param"><span class="keyword-only-separator o"><abbr title="Keyword-only parameters separator (PEP 3102)"><span class="pre">*</span></abbr></span></em>, <em class="sig-param"><span class="n"><span class="pre">file</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">depth</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">1</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">limit</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.print_call_graph" title="Link to this definition">¶</a></dt>
<dd><p>Print the async call graph for the current task or the provided
<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 <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>.</p>
<p>This function prints entries starting from the top frame and going
down towards the invocation point.</p>
<p>The function receives an optional <em>future</em> argument.
If not passed, the current running task will be used.</p>
<p>If the function is called on <em>the current task</em>, the optional
keyword-only <em>depth</em> argument can be used to skip the specified
number of frames from top of the stack.</p>
<p>If the optional keyword-only <em>limit</em> argument is provided, each call stack
in the resulting graph is truncated to include at most <code class="docutils literal notranslate"><span class="pre">abs(limit)</span></code>
entries. If <em>limit</em> is positive, the entries left are the closest to
the invocation point. If <em>limit</em> is negative, the topmost entries are
left. If <em>limit</em> is omitted or <code class="docutils literal notranslate"><span class="pre">None</span></code>, all entries are present.
If <em>limit</em> is <code class="docutils literal notranslate"><span class="pre">0</span></code>, the call stack is not printed at all, only
“awaited by” information is printed.</p>
<p>If <em>file</em> is omitted or <code class="docutils literal notranslate"><span class="pre">None</span></code>, the function will print
to <a class="reference internal" href="sys.html#sys.stdout" title="sys.stdout"><code class="xref py py-data docutils literal notranslate"><span class="pre">sys.stdout</span></code></a>.</p>
<p><strong>Example:</strong></p>
<p>The following Python code:</p>
<div class="highlight-python notranslate"><div class="highlight"><pre><span></span><span class="kn">import</span><span class="w"> </span><span class="nn">asyncio</span>

<span class="k">async</span> <span class="k">def</span><span class="w"> </span><span class="nf">test</span><span class="p">():</span>
    <span class="n">asyncio</span><span class="o">.</span><span class="n">print_call_graph</span><span class="p">()</span>

<span class="k">async</span> <span class="k">def</span><span class="w"> </span><span class="nf">main</span><span class="p">():</span>
    <span class="k">async</span> <span class="k">with</span> <span class="n">asyncio</span><span class="o">.</span><span class="n">TaskGroup</span><span class="p">()</span> <span class="k">as</span> <span class="n">g</span><span class="p">:</span>
        <span class="n">g</span><span class="o">.</span><span class="n">create_task</span><span class="p">(</span><span class="n">test</span><span class="p">(),</span> <span class="n">name</span><span class="o">=</span><span class="s1">&#39;test&#39;</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>
<p>will print:</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="o">*</span> <span class="n">Task</span><span class="p">(</span><span class="n">name</span><span class="o">=</span><span class="s1">&#39;test&#39;</span><span class="p">,</span> <span class="nb">id</span><span class="o">=</span><span class="mh">0x1039f0fe0</span><span class="p">)</span>
<span class="o">+</span> <span class="n">Call</span> <span class="n">stack</span><span class="p">:</span>
<span class="o">|</span>   <span class="n">File</span> <span class="s1">&#39;t2.py&#39;</span><span class="p">,</span> <span class="n">line</span> <span class="mi">4</span><span class="p">,</span> <span class="ow">in</span> <span class="k">async</span> <span class="n">test</span><span class="p">()</span>
<span class="o">+</span> <span class="n">Awaited</span> <span class="n">by</span><span class="p">:</span>
   <span class="o">*</span> <span class="n">Task</span><span class="p">(</span><span class="n">name</span><span class="o">=</span><span class="s1">&#39;Task-1&#39;</span><span class="p">,</span> <span class="nb">id</span><span class="o">=</span><span class="mh">0x103a5e060</span><span class="p">)</span>
      <span class="o">+</span> <span class="n">Call</span> <span class="n">stack</span><span class="p">:</span>
      <span class="o">|</span>   <span class="n">File</span> <span class="s1">&#39;taskgroups.py&#39;</span><span class="p">,</span> <span class="n">line</span> <span class="mi">107</span><span class="p">,</span> <span class="ow">in</span> <span class="k">async</span> <span class="n">TaskGroup</span><span class="o">.</span><span class="fm">__aexit__</span><span class="p">()</span>
      <span class="o">|</span>   <span class="n">File</span> <span class="s1">&#39;t2.py&#39;</span><span class="p">,</span> <span class="n">line</span> <span class="mi">7</span><span class="p">,</span> <span class="ow">in</span> <span class="k">async</span> <span class="n">main</span><span class="p">()</span>
</pre></div>
</div>
</dd></dl>

<dl class="py function">
<dt class="sig sig-object py" id="asyncio.format_call_graph">
<span class="sig-prename descclassname"><span class="pre">asyncio.</span></span><span class="sig-name descname"><span class="pre">format_call_graph</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">future</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="positional-only-separator o"><abbr title="Positional-only parameter separator (PEP 570)"><span class="pre">/</span></abbr></span></em>, <em class="sig-param"><span class="keyword-only-separator o"><abbr title="Keyword-only parameters separator (PEP 3102)"><span class="pre">*</span></abbr></span></em>, <em class="sig-param"><span class="n"><span class="pre">depth</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">1</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">limit</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.format_call_graph" title="Link to this definition">¶</a></dt>
<dd><p>Like <a class="reference internal" href="#asyncio.print_call_graph" title="asyncio.print_call_graph"><code class="xref py py-func docutils literal notranslate"><span class="pre">print_call_graph()</span></code></a>, but returns a string.
If <em>future</em> is <code class="docutils literal notranslate"><span class="pre">None</span></code> and there’s no current task,
the function returns an empty string.</p>
</dd></dl>

<dl class="py function">
<dt class="sig sig-object py" id="asyncio.capture_call_graph">
<span class="sig-prename descclassname"><span class="pre">asyncio.</span></span><span class="sig-name descname"><span class="pre">capture_call_graph</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">future</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="positional-only-separator o"><abbr title="Positional-only parameter separator (PEP 570)"><span class="pre">/</span></abbr></span></em>, <em class="sig-param"><span class="keyword-only-separator o"><abbr title="Keyword-only parameters separator (PEP 3102)"><span class="pre">*</span></abbr></span></em>, <em class="sig-param"><span class="n"><span class="pre">depth</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">1</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">limit</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.capture_call_graph" title="Link to this definition">¶</a></dt>
<dd><p>Capture the async call graph for the current task or the provided
<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 <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>.</p>
<p>The function receives an optional <em>future</em> argument.
If not passed, the current running task will be used. If there’s no
current task, the function returns <code class="docutils literal notranslate"><span class="pre">None</span></code>.</p>
<p>If the function is called on <em>the current task</em>, the optional
keyword-only <em>depth</em> argument can be used to skip the specified
number of frames from top of the stack.</p>
<p>Returns a <code class="docutils literal notranslate"><span class="pre">FutureCallGraph</span></code> data class object:</p>
<ul>
<li><p><code class="docutils literal notranslate"><span class="pre">FutureCallGraph(future,</span> <span class="pre">call_stack,</span> <span class="pre">awaited_by)</span></code></p>
<blockquote>
<div><p>Where <em>future</em> is a reference to 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> or
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 their subclasses.)</p>
<p><code class="docutils literal notranslate"><span class="pre">call_stack</span></code> is a tuple of <code class="docutils literal notranslate"><span class="pre">FrameCallGraphEntry</span></code> objects.</p>
<p><code class="docutils literal notranslate"><span class="pre">awaited_by</span></code> is a tuple of <code class="docutils literal notranslate"><span class="pre">FutureCallGraph</span></code> objects.</p>
</div></blockquote>
</li>
<li><p><code class="docutils literal notranslate"><span class="pre">FrameCallGraphEntry(frame)</span></code></p>
<blockquote>
<div><p>Where <em>frame</em> is a frame object of a regular Python function
in the call stack.</p>
</div></blockquote>
</li>
</ul>
</dd></dl>

<section id="low-level-utility-functions">
<h2>Low level utility functions<a class="headerlink" href="#low-level-utility-functions" title="Link to this heading">¶</a></h2>
<p>To introspect an async call graph asyncio requires cooperation from
control flow structures, such as <a class="reference internal" href="asyncio-task.html#asyncio.shield" title="asyncio.shield"><code class="xref py py-func docutils literal notranslate"><span class="pre">shield()</span></code></a> or <a class="reference internal" href="asyncio-task.html#asyncio.TaskGroup" title="asyncio.TaskGroup"><code class="xref py py-class docutils literal notranslate"><span class="pre">TaskGroup</span></code></a>.
Any time an intermediate <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> object with low-level APIs like
<a class="reference internal" href="asyncio-future.html#asyncio.Future.add_done_callback" title="asyncio.Future.add_done_callback"><code class="xref py py-meth docutils literal notranslate"><span class="pre">Future.add_done_callback()</span></code></a> is
involved, the following two functions should be used to inform asyncio
about how exactly such intermediate future objects are connected with
the tasks they wrap or control.</p>
<dl class="py function">
<dt class="sig sig-object py" id="asyncio.future_add_to_awaited_by">
<span class="sig-prename descclassname"><span class="pre">asyncio.</span></span><span class="sig-name descname"><span class="pre">future_add_to_awaited_by</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">future</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">waiter</span></span></em>, <em class="sig-param"><span class="positional-only-separator o"><abbr title="Positional-only parameter separator (PEP 570)"><span class="pre">/</span></abbr></span></em><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.future_add_to_awaited_by" title="Link to this definition">¶</a></dt>
<dd><p>Record that <em>future</em> is awaited on by <em>waiter</em>.</p>
<p>Both <em>future</em> and <em>waiter</em> must be instances 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> or <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 their subclasses,
otherwise the call would have no effect.</p>
<p>A call to <code class="docutils literal notranslate"><span class="pre">future_add_to_awaited_by()</span></code> must be followed by an
eventual call to the <a class="reference internal" href="#asyncio.future_discard_from_awaited_by" title="asyncio.future_discard_from_awaited_by"><code class="xref py py-func docutils literal notranslate"><span class="pre">future_discard_from_awaited_by()</span></code></a> function
with the same arguments.</p>
</dd></dl>

<dl class="py function">
<dt class="sig sig-object py" id="asyncio.future_discard_from_awaited_by">
<span class="sig-prename descclassname"><span class="pre">asyncio.</span></span><span class="sig-name descname"><span class="pre">future_discard_from_awaited_by</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">future</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">waiter</span></span></em>, <em class="sig-param"><span class="positional-only-separator o"><abbr title="Positional-only parameter separator (PEP 570)"><span class="pre">/</span></abbr></span></em><span class="sig-paren">)</span><a class="headerlink" href="#asyncio.future_discard_from_awaited_by" title="Link to this definition">¶</a></dt>
<dd><p>Record that <em>future</em> is no longer awaited on by <em>waiter</em>.</p>
<p>Both <em>future</em> and <em>waiter</em> must be instances 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> or <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 their subclasses, otherwise
the call would have no effect.</p>
</dd></dl>

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