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<div class="section" id="module-tracemalloc">
<span id="tracemalloc-trace-memory-allocations"></span><h1><a class="reference internal" href="#module-tracemalloc" title="tracemalloc: Trace memory allocations."><code class="xref py py-mod docutils literal notranslate"><span class="pre">tracemalloc</span></code></a> — Trace memory allocations<a class="headerlink" href="#module-tracemalloc" title="Permalink to this headline">¶</a></h1>
<div class="versionadded">
<p><span class="versionmodified added">New in version 3.4.</span></p>
</div>
<p><strong>Source code:</strong> <a class="reference external" href="https://github.com/python/cpython/tree/3.7/Lib/tracemalloc.py">Lib/tracemalloc.py</a></p>
<hr class="docutils" />
<p>The tracemalloc module is a debug tool to trace memory blocks allocated by
Python. It provides the following information:</p>
<ul class="simple">
<li><p>Traceback where an object was allocated</p></li>
<li><p>Statistics on allocated memory blocks per filename and per line number:
total size, number and average size of allocated memory blocks</p></li>
<li><p>Compute the differences between two snapshots to detect memory leaks</p></li>
</ul>
<p>To trace most memory blocks allocated by Python, the module should be started
as early as possible by setting the <span class="target" id="index-0"></span><a class="reference internal" href="../using/cmdline.html#envvar-PYTHONTRACEMALLOC"><code class="xref std std-envvar docutils literal notranslate"><span class="pre">PYTHONTRACEMALLOC</span></code></a> environment
variable to <code class="docutils literal notranslate"><span class="pre">1</span></code>, or by using <a class="reference internal" href="../using/cmdline.html#id5"><code class="xref std std-option docutils literal notranslate"><span class="pre">-X</span></code></a> <code class="docutils literal notranslate"><span class="pre">tracemalloc</span></code> command line
option. The <a class="reference internal" href="#tracemalloc.start" title="tracemalloc.start"><code class="xref py py-func docutils literal notranslate"><span class="pre">tracemalloc.start()</span></code></a> function can be called at runtime to
start tracing Python memory allocations.</p>
<p>By default, a trace of an allocated memory block only stores the most recent
frame (1 frame). To store 25 frames at startup: set the
<span class="target" id="index-1"></span><a class="reference internal" href="../using/cmdline.html#envvar-PYTHONTRACEMALLOC"><code class="xref std std-envvar docutils literal notranslate"><span class="pre">PYTHONTRACEMALLOC</span></code></a> environment variable to <code class="docutils literal notranslate"><span class="pre">25</span></code>, or use the
<a class="reference internal" href="../using/cmdline.html#id5"><code class="xref std std-option docutils literal notranslate"><span class="pre">-X</span></code></a> <code class="docutils literal notranslate"><span class="pre">tracemalloc=25</span></code> command line option.</p>
<div class="section" id="examples">
<h2>Examples<a class="headerlink" href="#examples" title="Permalink to this headline">¶</a></h2>
<div class="section" id="display-the-top-10">
<h3>Display the top 10<a class="headerlink" href="#display-the-top-10" title="Permalink to this headline">¶</a></h3>
<p>Display the 10 files allocating the most memory:</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="kn">import</span> <span class="nn">tracemalloc</span>
<span class="n">tracemalloc</span><span class="o">.</span><span class="n">start</span><span class="p">()</span>
<span class="c1"># ... run your application ...</span>
<span class="n">snapshot</span> <span class="o">=</span> <span class="n">tracemalloc</span><span class="o">.</span><span class="n">take_snapshot</span><span class="p">()</span>
<span class="n">top_stats</span> <span class="o">=</span> <span class="n">snapshot</span><span class="o">.</span><span class="n">statistics</span><span class="p">(</span><span class="s1">'lineno'</span><span class="p">)</span>
<span class="nb">print</span><span class="p">(</span><span class="s2">"[ Top 10 ]"</span><span class="p">)</span>
<span class="k">for</span> <span class="n">stat</span> <span class="ow">in</span> <span class="n">top_stats</span><span class="p">[:</span><span class="mi">10</span><span class="p">]:</span>
<span class="nb">print</span><span class="p">(</span><span class="n">stat</span><span class="p">)</span>
</pre></div>
</div>
<p>Example of output of the Python test suite:</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="p">[</span> <span class="n">Top</span> <span class="mi">10</span> <span class="p">]</span>
<span class="o"><</span><span class="n">frozen</span> <span class="n">importlib</span><span class="o">.</span><span class="n">_bootstrap</span><span class="o">></span><span class="p">:</span><span class="mi">716</span><span class="p">:</span> <span class="n">size</span><span class="o">=</span><span class="mi">4855</span> <span class="n">KiB</span><span class="p">,</span> <span class="n">count</span><span class="o">=</span><span class="mi">39328</span><span class="p">,</span> <span class="n">average</span><span class="o">=</span><span class="mi">126</span> <span class="n">B</span>
<span class="o"><</span><span class="n">frozen</span> <span class="n">importlib</span><span class="o">.</span><span class="n">_bootstrap</span><span class="o">></span><span class="p">:</span><span class="mi">284</span><span class="p">:</span> <span class="n">size</span><span class="o">=</span><span class="mi">521</span> <span class="n">KiB</span><span class="p">,</span> <span class="n">count</span><span class="o">=</span><span class="mi">3199</span><span class="p">,</span> <span class="n">average</span><span class="o">=</span><span class="mi">167</span> <span class="n">B</span>
<span class="o">/</span><span class="n">usr</span><span class="o">/</span><span class="n">lib</span><span class="o">/</span><span class="n">python3</span><span class="o">.</span><span class="mi">4</span><span class="o">/</span><span class="n">collections</span><span class="o">/</span><span class="fm">__init__</span><span class="o">.</span><span class="n">py</span><span class="p">:</span><span class="mi">368</span><span class="p">:</span> <span class="n">size</span><span class="o">=</span><span class="mi">244</span> <span class="n">KiB</span><span class="p">,</span> <span class="n">count</span><span class="o">=</span><span class="mi">2315</span><span class="p">,</span> <span class="n">average</span><span class="o">=</span><span class="mi">108</span> <span class="n">B</span>
<span class="o">/</span><span class="n">usr</span><span class="o">/</span><span class="n">lib</span><span class="o">/</span><span class="n">python3</span><span class="o">.</span><span class="mi">4</span><span class="o">/</span><span class="n">unittest</span><span class="o">/</span><span class="n">case</span><span class="o">.</span><span class="n">py</span><span class="p">:</span><span class="mi">381</span><span class="p">:</span> <span class="n">size</span><span class="o">=</span><span class="mi">185</span> <span class="n">KiB</span><span class="p">,</span> <span class="n">count</span><span class="o">=</span><span class="mi">779</span><span class="p">,</span> <span class="n">average</span><span class="o">=</span><span class="mi">243</span> <span class="n">B</span>
<span class="o">/</span><span class="n">usr</span><span class="o">/</span><span class="n">lib</span><span class="o">/</span><span class="n">python3</span><span class="o">.</span><span class="mi">4</span><span class="o">/</span><span class="n">unittest</span><span class="o">/</span><span class="n">case</span><span class="o">.</span><span class="n">py</span><span class="p">:</span><span class="mi">402</span><span class="p">:</span> <span class="n">size</span><span class="o">=</span><span class="mi">154</span> <span class="n">KiB</span><span class="p">,</span> <span class="n">count</span><span class="o">=</span><span class="mi">378</span><span class="p">,</span> <span class="n">average</span><span class="o">=</span><span class="mi">416</span> <span class="n">B</span>
<span class="o">/</span><span class="n">usr</span><span class="o">/</span><span class="n">lib</span><span class="o">/</span><span class="n">python3</span><span class="o">.</span><span class="mi">4</span><span class="o">/</span><span class="n">abc</span><span class="o">.</span><span class="n">py</span><span class="p">:</span><span class="mi">133</span><span class="p">:</span> <span class="n">size</span><span class="o">=</span><span class="mf">88.7</span> <span class="n">KiB</span><span class="p">,</span> <span class="n">count</span><span class="o">=</span><span class="mi">347</span><span class="p">,</span> <span class="n">average</span><span class="o">=</span><span class="mi">262</span> <span class="n">B</span>
<span class="o"><</span><span class="n">frozen</span> <span class="n">importlib</span><span class="o">.</span><span class="n">_bootstrap</span><span class="o">></span><span class="p">:</span><span class="mi">1446</span><span class="p">:</span> <span class="n">size</span><span class="o">=</span><span class="mf">70.4</span> <span class="n">KiB</span><span class="p">,</span> <span class="n">count</span><span class="o">=</span><span class="mi">911</span><span class="p">,</span> <span class="n">average</span><span class="o">=</span><span class="mi">79</span> <span class="n">B</span>
<span class="o"><</span><span class="n">frozen</span> <span class="n">importlib</span><span class="o">.</span><span class="n">_bootstrap</span><span class="o">></span><span class="p">:</span><span class="mi">1454</span><span class="p">:</span> <span class="n">size</span><span class="o">=</span><span class="mf">52.0</span> <span class="n">KiB</span><span class="p">,</span> <span class="n">count</span><span class="o">=</span><span class="mi">25</span><span class="p">,</span> <span class="n">average</span><span class="o">=</span><span class="mi">2131</span> <span class="n">B</span>
<span class="o"><</span><span class="n">string</span><span class="o">></span><span class="p">:</span><span class="mi">5</span><span class="p">:</span> <span class="n">size</span><span class="o">=</span><span class="mf">49.7</span> <span class="n">KiB</span><span class="p">,</span> <span class="n">count</span><span class="o">=</span><span class="mi">148</span><span class="p">,</span> <span class="n">average</span><span class="o">=</span><span class="mi">344</span> <span class="n">B</span>
<span class="o">/</span><span class="n">usr</span><span class="o">/</span><span class="n">lib</span><span class="o">/</span><span class="n">python3</span><span class="o">.</span><span class="mi">4</span><span class="o">/</span><span class="n">sysconfig</span><span class="o">.</span><span class="n">py</span><span class="p">:</span><span class="mi">411</span><span class="p">:</span> <span class="n">size</span><span class="o">=</span><span class="mf">48.0</span> <span class="n">KiB</span><span class="p">,</span> <span class="n">count</span><span class="o">=</span><span class="mi">1</span><span class="p">,</span> <span class="n">average</span><span class="o">=</span><span class="mf">48.0</span> <span class="n">KiB</span>
</pre></div>
</div>
<p>We can see that Python loaded <code class="docutils literal notranslate"><span class="pre">4855</span> <span class="pre">KiB</span></code> data (bytecode and constants) from
modules and that the <a class="reference internal" href="collections.html#module-collections" title="collections: Container datatypes"><code class="xref py py-mod docutils literal notranslate"><span class="pre">collections</span></code></a> module allocated <code class="docutils literal notranslate"><span class="pre">244</span> <span class="pre">KiB</span></code> to build
<a class="reference internal" href="collections.html#collections.namedtuple" title="collections.namedtuple"><code class="xref py py-class docutils literal notranslate"><span class="pre">namedtuple</span></code></a> types.</p>
<p>See <a class="reference internal" href="#tracemalloc.Snapshot.statistics" title="tracemalloc.Snapshot.statistics"><code class="xref py py-meth docutils literal notranslate"><span class="pre">Snapshot.statistics()</span></code></a> for more options.</p>
</div>
<div class="section" id="compute-differences">
<h3>Compute differences<a class="headerlink" href="#compute-differences" title="Permalink to this headline">¶</a></h3>
<p>Take two snapshots and display the differences:</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="kn">import</span> <span class="nn">tracemalloc</span>
<span class="n">tracemalloc</span><span class="o">.</span><span class="n">start</span><span class="p">()</span>
<span class="c1"># ... start your application ...</span>
<span class="n">snapshot1</span> <span class="o">=</span> <span class="n">tracemalloc</span><span class="o">.</span><span class="n">take_snapshot</span><span class="p">()</span>
<span class="c1"># ... call the function leaking memory ...</span>
<span class="n">snapshot2</span> <span class="o">=</span> <span class="n">tracemalloc</span><span class="o">.</span><span class="n">take_snapshot</span><span class="p">()</span>
<span class="n">top_stats</span> <span class="o">=</span> <span class="n">snapshot2</span><span class="o">.</span><span class="n">compare_to</span><span class="p">(</span><span class="n">snapshot1</span><span class="p">,</span> <span class="s1">'lineno'</span><span class="p">)</span>
<span class="nb">print</span><span class="p">(</span><span class="s2">"[ Top 10 differences ]"</span><span class="p">)</span>
<span class="k">for</span> <span class="n">stat</span> <span class="ow">in</span> <span class="n">top_stats</span><span class="p">[:</span><span class="mi">10</span><span class="p">]:</span>
<span class="nb">print</span><span class="p">(</span><span class="n">stat</span><span class="p">)</span>
</pre></div>
</div>
<p>Example of output before/after running some tests of the Python test suite:</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="p">[</span> <span class="n">Top</span> <span class="mi">10</span> <span class="n">differences</span> <span class="p">]</span>
<span class="o"><</span><span class="n">frozen</span> <span class="n">importlib</span><span class="o">.</span><span class="n">_bootstrap</span><span class="o">></span><span class="p">:</span><span class="mi">716</span><span class="p">:</span> <span class="n">size</span><span class="o">=</span><span class="mi">8173</span> <span class="n">KiB</span> <span class="p">(</span><span class="o">+</span><span class="mi">4428</span> <span class="n">KiB</span><span class="p">),</span> <span class="n">count</span><span class="o">=</span><span class="mi">71332</span> <span class="p">(</span><span class="o">+</span><span class="mi">39369</span><span class="p">),</span> <span class="n">average</span><span class="o">=</span><span class="mi">117</span> <span class="n">B</span>
<span class="o">/</span><span class="n">usr</span><span class="o">/</span><span class="n">lib</span><span class="o">/</span><span class="n">python3</span><span class="o">.</span><span class="mi">4</span><span class="o">/</span><span class="n">linecache</span><span class="o">.</span><span class="n">py</span><span class="p">:</span><span class="mi">127</span><span class="p">:</span> <span class="n">size</span><span class="o">=</span><span class="mi">940</span> <span class="n">KiB</span> <span class="p">(</span><span class="o">+</span><span class="mi">940</span> <span class="n">KiB</span><span class="p">),</span> <span class="n">count</span><span class="o">=</span><span class="mi">8106</span> <span class="p">(</span><span class="o">+</span><span class="mi">8106</span><span class="p">),</span> <span class="n">average</span><span class="o">=</span><span class="mi">119</span> <span class="n">B</span>
<span class="o">/</span><span class="n">usr</span><span class="o">/</span><span class="n">lib</span><span class="o">/</span><span class="n">python3</span><span class="o">.</span><span class="mi">4</span><span class="o">/</span><span class="n">unittest</span><span class="o">/</span><span class="n">case</span><span class="o">.</span><span class="n">py</span><span class="p">:</span><span class="mi">571</span><span class="p">:</span> <span class="n">size</span><span class="o">=</span><span class="mi">298</span> <span class="n">KiB</span> <span class="p">(</span><span class="o">+</span><span class="mi">298</span> <span class="n">KiB</span><span class="p">),</span> <span class="n">count</span><span class="o">=</span><span class="mi">589</span> <span class="p">(</span><span class="o">+</span><span class="mi">589</span><span class="p">),</span> <span class="n">average</span><span class="o">=</span><span class="mi">519</span> <span class="n">B</span>
<span class="o"><</span><span class="n">frozen</span> <span class="n">importlib</span><span class="o">.</span><span class="n">_bootstrap</span><span class="o">></span><span class="p">:</span><span class="mi">284</span><span class="p">:</span> <span class="n">size</span><span class="o">=</span><span class="mi">1005</span> <span class="n">KiB</span> <span class="p">(</span><span class="o">+</span><span class="mi">166</span> <span class="n">KiB</span><span class="p">),</span> <span class="n">count</span><span class="o">=</span><span class="mi">7423</span> <span class="p">(</span><span class="o">+</span><span class="mi">1526</span><span class="p">),</span> <span class="n">average</span><span class="o">=</span><span class="mi">139</span> <span class="n">B</span>
<span class="o">/</span><span class="n">usr</span><span class="o">/</span><span class="n">lib</span><span class="o">/</span><span class="n">python3</span><span class="o">.</span><span class="mi">4</span><span class="o">/</span><span class="n">mimetypes</span><span class="o">.</span><span class="n">py</span><span class="p">:</span><span class="mi">217</span><span class="p">:</span> <span class="n">size</span><span class="o">=</span><span class="mi">112</span> <span class="n">KiB</span> <span class="p">(</span><span class="o">+</span><span class="mi">112</span> <span class="n">KiB</span><span class="p">),</span> <span class="n">count</span><span class="o">=</span><span class="mi">1334</span> <span class="p">(</span><span class="o">+</span><span class="mi">1334</span><span class="p">),</span> <span class="n">average</span><span class="o">=</span><span class="mi">86</span> <span class="n">B</span>
<span class="o">/</span><span class="n">usr</span><span class="o">/</span><span class="n">lib</span><span class="o">/</span><span class="n">python3</span><span class="o">.</span><span class="mi">4</span><span class="o">/</span><span class="n">http</span><span class="o">/</span><span class="n">server</span><span class="o">.</span><span class="n">py</span><span class="p">:</span><span class="mi">848</span><span class="p">:</span> <span class="n">size</span><span class="o">=</span><span class="mf">96.0</span> <span class="n">KiB</span> <span class="p">(</span><span class="o">+</span><span class="mf">96.0</span> <span class="n">KiB</span><span class="p">),</span> <span class="n">count</span><span class="o">=</span><span class="mi">1</span> <span class="p">(</span><span class="o">+</span><span class="mi">1</span><span class="p">),</span> <span class="n">average</span><span class="o">=</span><span class="mf">96.0</span> <span class="n">KiB</span>
<span class="o">/</span><span class="n">usr</span><span class="o">/</span><span class="n">lib</span><span class="o">/</span><span class="n">python3</span><span class="o">.</span><span class="mi">4</span><span class="o">/</span><span class="n">inspect</span><span class="o">.</span><span class="n">py</span><span class="p">:</span><span class="mi">1465</span><span class="p">:</span> <span class="n">size</span><span class="o">=</span><span class="mf">83.5</span> <span class="n">KiB</span> <span class="p">(</span><span class="o">+</span><span class="mf">83.5</span> <span class="n">KiB</span><span class="p">),</span> <span class="n">count</span><span class="o">=</span><span class="mi">109</span> <span class="p">(</span><span class="o">+</span><span class="mi">109</span><span class="p">),</span> <span class="n">average</span><span class="o">=</span><span class="mi">784</span> <span class="n">B</span>
<span class="o">/</span><span class="n">usr</span><span class="o">/</span><span class="n">lib</span><span class="o">/</span><span class="n">python3</span><span class="o">.</span><span class="mi">4</span><span class="o">/</span><span class="n">unittest</span><span class="o">/</span><span class="n">mock</span><span class="o">.</span><span class="n">py</span><span class="p">:</span><span class="mi">491</span><span class="p">:</span> <span class="n">size</span><span class="o">=</span><span class="mf">77.7</span> <span class="n">KiB</span> <span class="p">(</span><span class="o">+</span><span class="mf">77.7</span> <span class="n">KiB</span><span class="p">),</span> <span class="n">count</span><span class="o">=</span><span class="mi">143</span> <span class="p">(</span><span class="o">+</span><span class="mi">143</span><span class="p">),</span> <span class="n">average</span><span class="o">=</span><span class="mi">557</span> <span class="n">B</span>
<span class="o">/</span><span class="n">usr</span><span class="o">/</span><span class="n">lib</span><span class="o">/</span><span class="n">python3</span><span class="o">.</span><span class="mi">4</span><span class="o">/</span><span class="n">urllib</span><span class="o">/</span><span class="n">parse</span><span class="o">.</span><span class="n">py</span><span class="p">:</span><span class="mi">476</span><span class="p">:</span> <span class="n">size</span><span class="o">=</span><span class="mf">71.8</span> <span class="n">KiB</span> <span class="p">(</span><span class="o">+</span><span class="mf">71.8</span> <span class="n">KiB</span><span class="p">),</span> <span class="n">count</span><span class="o">=</span><span class="mi">969</span> <span class="p">(</span><span class="o">+</span><span class="mi">969</span><span class="p">),</span> <span class="n">average</span><span class="o">=</span><span class="mi">76</span> <span class="n">B</span>
<span class="o">/</span><span class="n">usr</span><span class="o">/</span><span class="n">lib</span><span class="o">/</span><span class="n">python3</span><span class="o">.</span><span class="mi">4</span><span class="o">/</span><span class="n">contextlib</span><span class="o">.</span><span class="n">py</span><span class="p">:</span><span class="mi">38</span><span class="p">:</span> <span class="n">size</span><span class="o">=</span><span class="mf">67.2</span> <span class="n">KiB</span> <span class="p">(</span><span class="o">+</span><span class="mf">67.2</span> <span class="n">KiB</span><span class="p">),</span> <span class="n">count</span><span class="o">=</span><span class="mi">126</span> <span class="p">(</span><span class="o">+</span><span class="mi">126</span><span class="p">),</span> <span class="n">average</span><span class="o">=</span><span class="mi">546</span> <span class="n">B</span>
</pre></div>
</div>
<p>We can see that Python has loaded <code class="docutils literal notranslate"><span class="pre">8173</span> <span class="pre">KiB</span></code> of module data (bytecode and
constants), and that this is <code class="docutils literal notranslate"><span class="pre">4428</span> <span class="pre">KiB</span></code> more than had been loaded before the
tests, when the previous snapshot was taken. Similarly, the <a class="reference internal" href="linecache.html#module-linecache" title="linecache: Provides random access to individual lines from text files."><code class="xref py py-mod docutils literal notranslate"><span class="pre">linecache</span></code></a>
module has cached <code class="docutils literal notranslate"><span class="pre">940</span> <span class="pre">KiB</span></code> of Python source code to format tracebacks, all
of it since the previous snapshot.</p>
<p>If the system has little free memory, snapshots can be written on disk using
the <a class="reference internal" href="#tracemalloc.Snapshot.dump" title="tracemalloc.Snapshot.dump"><code class="xref py py-meth docutils literal notranslate"><span class="pre">Snapshot.dump()</span></code></a> method to analyze the snapshot offline. Then use the
<a class="reference internal" href="#tracemalloc.Snapshot.load" title="tracemalloc.Snapshot.load"><code class="xref py py-meth docutils literal notranslate"><span class="pre">Snapshot.load()</span></code></a> method reload the snapshot.</p>
</div>
<div class="section" id="get-the-traceback-of-a-memory-block">
<h3>Get the traceback of a memory block<a class="headerlink" href="#get-the-traceback-of-a-memory-block" title="Permalink to this headline">¶</a></h3>
<p>Code to display the traceback of the biggest memory block:</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="kn">import</span> <span class="nn">tracemalloc</span>
<span class="c1"># Store 25 frames</span>
<span class="n">tracemalloc</span><span class="o">.</span><span class="n">start</span><span class="p">(</span><span class="mi">25</span><span class="p">)</span>
<span class="c1"># ... run your application ...</span>
<span class="n">snapshot</span> <span class="o">=</span> <span class="n">tracemalloc</span><span class="o">.</span><span class="n">take_snapshot</span><span class="p">()</span>
<span class="n">top_stats</span> <span class="o">=</span> <span class="n">snapshot</span><span class="o">.</span><span class="n">statistics</span><span class="p">(</span><span class="s1">'traceback'</span><span class="p">)</span>
<span class="c1"># pick the biggest memory block</span>
<span class="n">stat</span> <span class="o">=</span> <span class="n">top_stats</span><span class="p">[</span><span class="mi">0</span><span class="p">]</span>
<span class="nb">print</span><span class="p">(</span><span class="s2">"</span><span class="si">%s</span><span class="s2"> memory blocks: </span><span class="si">%.1f</span><span class="s2"> KiB"</span> <span class="o">%</span> <span class="p">(</span><span class="n">stat</span><span class="o">.</span><span class="n">count</span><span class="p">,</span> <span class="n">stat</span><span class="o">.</span><span class="n">size</span> <span class="o">/</span> <span class="mi">1024</span><span class="p">))</span>
<span class="k">for</span> <span class="n">line</span> <span class="ow">in</span> <span class="n">stat</span><span class="o">.</span><span class="n">traceback</span><span class="o">.</span><span class="n">format</span><span class="p">():</span>
<span class="nb">print</span><span class="p">(</span><span class="n">line</span><span class="p">)</span>
</pre></div>
</div>
<p>Example of output of the Python test suite (traceback limited to 25 frames):</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="mi">903</span> <span class="n">memory</span> <span class="n">blocks</span><span class="p">:</span> <span class="mf">870.1</span> <span class="n">KiB</span>
<span class="n">File</span> <span class="s2">"<frozen importlib._bootstrap>"</span><span class="p">,</span> <span class="n">line</span> <span class="mi">716</span>
<span class="n">File</span> <span class="s2">"<frozen importlib._bootstrap>"</span><span class="p">,</span> <span class="n">line</span> <span class="mi">1036</span>
<span class="n">File</span> <span class="s2">"<frozen importlib._bootstrap>"</span><span class="p">,</span> <span class="n">line</span> <span class="mi">934</span>
<span class="n">File</span> <span class="s2">"<frozen importlib._bootstrap>"</span><span class="p">,</span> <span class="n">line</span> <span class="mi">1068</span>
<span class="n">File</span> <span class="s2">"<frozen importlib._bootstrap>"</span><span class="p">,</span> <span class="n">line</span> <span class="mi">619</span>
<span class="n">File</span> <span class="s2">"<frozen importlib._bootstrap>"</span><span class="p">,</span> <span class="n">line</span> <span class="mi">1581</span>
<span class="n">File</span> <span class="s2">"<frozen importlib._bootstrap>"</span><span class="p">,</span> <span class="n">line</span> <span class="mi">1614</span>
<span class="n">File</span> <span class="s2">"/usr/lib/python3.4/doctest.py"</span><span class="p">,</span> <span class="n">line</span> <span class="mi">101</span>
<span class="kn">import</span> <span class="nn">pdb</span>
<span class="n">File</span> <span class="s2">"<frozen importlib._bootstrap>"</span><span class="p">,</span> <span class="n">line</span> <span class="mi">284</span>
<span class="n">File</span> <span class="s2">"<frozen importlib._bootstrap>"</span><span class="p">,</span> <span class="n">line</span> <span class="mi">938</span>
<span class="n">File</span> <span class="s2">"<frozen importlib._bootstrap>"</span><span class="p">,</span> <span class="n">line</span> <span class="mi">1068</span>
<span class="n">File</span> <span class="s2">"<frozen importlib._bootstrap>"</span><span class="p">,</span> <span class="n">line</span> <span class="mi">619</span>
<span class="n">File</span> <span class="s2">"<frozen importlib._bootstrap>"</span><span class="p">,</span> <span class="n">line</span> <span class="mi">1581</span>
<span class="n">File</span> <span class="s2">"<frozen importlib._bootstrap>"</span><span class="p">,</span> <span class="n">line</span> <span class="mi">1614</span>
<span class="n">File</span> <span class="s2">"/usr/lib/python3.4/test/support/__init__.py"</span><span class="p">,</span> <span class="n">line</span> <span class="mi">1728</span>
<span class="kn">import</span> <span class="nn">doctest</span>
<span class="n">File</span> <span class="s2">"/usr/lib/python3.4/test/test_pickletools.py"</span><span class="p">,</span> <span class="n">line</span> <span class="mi">21</span>
<span class="n">support</span><span class="o">.</span><span class="n">run_doctest</span><span class="p">(</span><span class="n">pickletools</span><span class="p">)</span>
<span class="n">File</span> <span class="s2">"/usr/lib/python3.4/test/regrtest.py"</span><span class="p">,</span> <span class="n">line</span> <span class="mi">1276</span>
<span class="n">test_runner</span><span class="p">()</span>
<span class="n">File</span> <span class="s2">"/usr/lib/python3.4/test/regrtest.py"</span><span class="p">,</span> <span class="n">line</span> <span class="mi">976</span>
<span class="n">display_failure</span><span class="o">=</span><span class="ow">not</span> <span class="n">verbose</span><span class="p">)</span>
<span class="n">File</span> <span class="s2">"/usr/lib/python3.4/test/regrtest.py"</span><span class="p">,</span> <span class="n">line</span> <span class="mi">761</span>
<span class="n">match_tests</span><span class="o">=</span><span class="n">ns</span><span class="o">.</span><span class="n">match_tests</span><span class="p">)</span>
<span class="n">File</span> <span class="s2">"/usr/lib/python3.4/test/regrtest.py"</span><span class="p">,</span> <span class="n">line</span> <span class="mi">1563</span>
<span class="n">main</span><span class="p">()</span>
<span class="n">File</span> <span class="s2">"/usr/lib/python3.4/test/__main__.py"</span><span class="p">,</span> <span class="n">line</span> <span class="mi">3</span>
<span class="n">regrtest</span><span class="o">.</span><span class="n">main_in_temp_cwd</span><span class="p">()</span>
<span class="n">File</span> <span class="s2">"/usr/lib/python3.4/runpy.py"</span><span class="p">,</span> <span class="n">line</span> <span class="mi">73</span>
<span class="n">exec</span><span class="p">(</span><span class="n">code</span><span class="p">,</span> <span class="n">run_globals</span><span class="p">)</span>
<span class="n">File</span> <span class="s2">"/usr/lib/python3.4/runpy.py"</span><span class="p">,</span> <span class="n">line</span> <span class="mi">160</span>
<span class="s2">"__main__"</span><span class="p">,</span> <span class="n">fname</span><span class="p">,</span> <span class="n">loader</span><span class="p">,</span> <span class="n">pkg_name</span><span class="p">)</span>
</pre></div>
</div>
<p>We can see that the most memory was allocated in the <a class="reference internal" href="importlib.html#module-importlib" title="importlib: The implementation of the import machinery."><code class="xref py py-mod docutils literal notranslate"><span class="pre">importlib</span></code></a> module to
load data (bytecode and constants) from modules: <code class="docutils literal notranslate"><span class="pre">870.1</span> <span class="pre">KiB</span></code>. The traceback is
where the <a class="reference internal" href="importlib.html#module-importlib" title="importlib: The implementation of the import machinery."><code class="xref py py-mod docutils literal notranslate"><span class="pre">importlib</span></code></a> loaded data most recently: on the <code class="docutils literal notranslate"><span class="pre">import</span> <span class="pre">pdb</span></code>
line of the <a class="reference internal" href="doctest.html#module-doctest" title="doctest: Test pieces of code within docstrings."><code class="xref py py-mod docutils literal notranslate"><span class="pre">doctest</span></code></a> module. The traceback may change if a new module is
loaded.</p>
</div>
<div class="section" id="pretty-top">
<h3>Pretty top<a class="headerlink" href="#pretty-top" title="Permalink to this headline">¶</a></h3>
<p>Code to display the 10 lines allocating the most memory with a pretty output,
ignoring <code class="docutils literal notranslate"><span class="pre"><frozen</span> <span class="pre">importlib._bootstrap></span></code> and <code class="docutils literal notranslate"><span class="pre"><unknown></span></code> files:</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="kn">import</span> <span class="nn">linecache</span>
<span class="kn">import</span> <span class="nn">os</span>
<span class="kn">import</span> <span class="nn">tracemalloc</span>
<span class="k">def</span> <span class="nf">display_top</span><span class="p">(</span><span class="n">snapshot</span><span class="p">,</span> <span class="n">key_type</span><span class="o">=</span><span class="s1">'lineno'</span><span class="p">,</span> <span class="n">limit</span><span class="o">=</span><span class="mi">10</span><span class="p">):</span>
<span class="n">snapshot</span> <span class="o">=</span> <span class="n">snapshot</span><span class="o">.</span><span class="n">filter_traces</span><span class="p">((</span>
<span class="n">tracemalloc</span><span class="o">.</span><span class="n">Filter</span><span class="p">(</span><span class="kc">False</span><span class="p">,</span> <span class="s2">"<frozen importlib._bootstrap>"</span><span class="p">),</span>
<span class="n">tracemalloc</span><span class="o">.</span><span class="n">Filter</span><span class="p">(</span><span class="kc">False</span><span class="p">,</span> <span class="s2">"<unknown>"</span><span class="p">),</span>
<span class="p">))</span>
<span class="n">top_stats</span> <span class="o">=</span> <span class="n">snapshot</span><span class="o">.</span><span class="n">statistics</span><span class="p">(</span><span class="n">key_type</span><span class="p">)</span>
<span class="nb">print</span><span class="p">(</span><span class="s2">"Top </span><span class="si">%s</span><span class="s2"> lines"</span> <span class="o">%</span> <span class="n">limit</span><span class="p">)</span>
<span class="k">for</span> <span class="n">index</span><span class="p">,</span> <span class="n">stat</span> <span class="ow">in</span> <span class="nb">enumerate</span><span class="p">(</span><span class="n">top_stats</span><span class="p">[:</span><span class="n">limit</span><span class="p">],</span> <span class="mi">1</span><span class="p">):</span>
<span class="n">frame</span> <span class="o">=</span> <span class="n">stat</span><span class="o">.</span><span class="n">traceback</span><span class="p">[</span><span class="mi">0</span><span class="p">]</span>
<span class="nb">print</span><span class="p">(</span><span class="s2">"#</span><span class="si">%s</span><span class="s2">: </span><span class="si">%s</span><span class="s2">:</span><span class="si">%s</span><span class="s2">: </span><span class="si">%.1f</span><span class="s2"> KiB"</span>
<span class="o">%</span> <span class="p">(</span><span class="n">index</span><span class="p">,</span> <span class="n">frame</span><span class="o">.</span><span class="n">filename</span><span class="p">,</span> <span class="n">frame</span><span class="o">.</span><span class="n">lineno</span><span class="p">,</span> <span class="n">stat</span><span class="o">.</span><span class="n">size</span> <span class="o">/</span> <span class="mi">1024</span><span class="p">))</span>
<span class="n">line</span> <span class="o">=</span> <span class="n">linecache</span><span class="o">.</span><span class="n">getline</span><span class="p">(</span><span class="n">frame</span><span class="o">.</span><span class="n">filename</span><span class="p">,</span> <span class="n">frame</span><span class="o">.</span><span class="n">lineno</span><span class="p">)</span><span class="o">.</span><span class="n">strip</span><span class="p">()</span>
<span class="k">if</span> <span class="n">line</span><span class="p">:</span>
<span class="nb">print</span><span class="p">(</span><span class="s1">' </span><span class="si">%s</span><span class="s1">'</span> <span class="o">%</span> <span class="n">line</span><span class="p">)</span>
<span class="n">other</span> <span class="o">=</span> <span class="n">top_stats</span><span class="p">[</span><span class="n">limit</span><span class="p">:]</span>
<span class="k">if</span> <span class="n">other</span><span class="p">:</span>
<span class="n">size</span> <span class="o">=</span> <span class="nb">sum</span><span class="p">(</span><span class="n">stat</span><span class="o">.</span><span class="n">size</span> <span class="k">for</span> <span class="n">stat</span> <span class="ow">in</span> <span class="n">other</span><span class="p">)</span>
<span class="nb">print</span><span class="p">(</span><span class="s2">"</span><span class="si">%s</span><span class="s2"> other: </span><span class="si">%.1f</span><span class="s2"> KiB"</span> <span class="o">%</span> <span class="p">(</span><span class="nb">len</span><span class="p">(</span><span class="n">other</span><span class="p">),</span> <span class="n">size</span> <span class="o">/</span> <span class="mi">1024</span><span class="p">))</span>
<span class="n">total</span> <span class="o">=</span> <span class="nb">sum</span><span class="p">(</span><span class="n">stat</span><span class="o">.</span><span class="n">size</span> <span class="k">for</span> <span class="n">stat</span> <span class="ow">in</span> <span class="n">top_stats</span><span class="p">)</span>
<span class="nb">print</span><span class="p">(</span><span class="s2">"Total allocated size: </span><span class="si">%.1f</span><span class="s2"> KiB"</span> <span class="o">%</span> <span class="p">(</span><span class="n">total</span> <span class="o">/</span> <span class="mi">1024</span><span class="p">))</span>
<span class="n">tracemalloc</span><span class="o">.</span><span class="n">start</span><span class="p">()</span>
<span class="c1"># ... run your application ...</span>
<span class="n">snapshot</span> <span class="o">=</span> <span class="n">tracemalloc</span><span class="o">.</span><span class="n">take_snapshot</span><span class="p">()</span>
<span class="n">display_top</span><span class="p">(</span><span class="n">snapshot</span><span class="p">)</span>
</pre></div>
</div>
<p>Example of output of the Python test suite:</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="n">Top</span> <span class="mi">10</span> <span class="n">lines</span>
<span class="c1">#1: Lib/base64.py:414: 419.8 KiB</span>
<span class="n">_b85chars2</span> <span class="o">=</span> <span class="p">[(</span><span class="n">a</span> <span class="o">+</span> <span class="n">b</span><span class="p">)</span> <span class="k">for</span> <span class="n">a</span> <span class="ow">in</span> <span class="n">_b85chars</span> <span class="k">for</span> <span class="n">b</span> <span class="ow">in</span> <span class="n">_b85chars</span><span class="p">]</span>
<span class="c1">#2: Lib/base64.py:306: 419.8 KiB</span>
<span class="n">_a85chars2</span> <span class="o">=</span> <span class="p">[(</span><span class="n">a</span> <span class="o">+</span> <span class="n">b</span><span class="p">)</span> <span class="k">for</span> <span class="n">a</span> <span class="ow">in</span> <span class="n">_a85chars</span> <span class="k">for</span> <span class="n">b</span> <span class="ow">in</span> <span class="n">_a85chars</span><span class="p">]</span>
<span class="c1">#3: collections/__init__.py:368: 293.6 KiB</span>
<span class="n">exec</span><span class="p">(</span><span class="n">class_definition</span><span class="p">,</span> <span class="n">namespace</span><span class="p">)</span>
<span class="c1">#4: Lib/abc.py:133: 115.2 KiB</span>
<span class="bp">cls</span> <span class="o">=</span> <span class="nb">super</span><span class="p">()</span><span class="o">.</span><span class="fm">__new__</span><span class="p">(</span><span class="n">mcls</span><span class="p">,</span> <span class="n">name</span><span class="p">,</span> <span class="n">bases</span><span class="p">,</span> <span class="n">namespace</span><span class="p">)</span>
<span class="c1">#5: unittest/case.py:574: 103.1 KiB</span>
<span class="n">testMethod</span><span class="p">()</span>
<span class="c1">#6: Lib/linecache.py:127: 95.4 KiB</span>
<span class="n">lines</span> <span class="o">=</span> <span class="n">fp</span><span class="o">.</span><span class="n">readlines</span><span class="p">()</span>
<span class="c1">#7: urllib/parse.py:476: 71.8 KiB</span>
<span class="k">for</span> <span class="n">a</span> <span class="ow">in</span> <span class="n">_hexdig</span> <span class="k">for</span> <span class="n">b</span> <span class="ow">in</span> <span class="n">_hexdig</span><span class="p">}</span>
<span class="c1">#8: <string>:5: 62.0 KiB</span>
<span class="c1">#9: Lib/_weakrefset.py:37: 60.0 KiB</span>
<span class="bp">self</span><span class="o">.</span><span class="n">data</span> <span class="o">=</span> <span class="nb">set</span><span class="p">()</span>
<span class="c1">#10: Lib/base64.py:142: 59.8 KiB</span>
<span class="n">_b32tab2</span> <span class="o">=</span> <span class="p">[</span><span class="n">a</span> <span class="o">+</span> <span class="n">b</span> <span class="k">for</span> <span class="n">a</span> <span class="ow">in</span> <span class="n">_b32tab</span> <span class="k">for</span> <span class="n">b</span> <span class="ow">in</span> <span class="n">_b32tab</span><span class="p">]</span>
<span class="mi">6220</span> <span class="n">other</span><span class="p">:</span> <span class="mf">3602.8</span> <span class="n">KiB</span>
<span class="n">Total</span> <span class="n">allocated</span> <span class="n">size</span><span class="p">:</span> <span class="mf">5303.1</span> <span class="n">KiB</span>
</pre></div>
</div>
<p>See <a class="reference internal" href="#tracemalloc.Snapshot.statistics" title="tracemalloc.Snapshot.statistics"><code class="xref py py-meth docutils literal notranslate"><span class="pre">Snapshot.statistics()</span></code></a> for more options.</p>
</div>
</div>
<div class="section" id="api">
<h2>API<a class="headerlink" href="#api" title="Permalink to this headline">¶</a></h2>
<div class="section" id="functions">
<h3>Functions<a class="headerlink" href="#functions" title="Permalink to this headline">¶</a></h3>
<dl class="function">
<dt id="tracemalloc.clear_traces">
<code class="sig-prename descclassname">tracemalloc.</code><code class="sig-name descname">clear_traces</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#tracemalloc.clear_traces" title="Permalink to this definition">¶</a></dt>
<dd><p>Clear traces of memory blocks allocated by Python.</p>
<p>See also <a class="reference internal" href="#tracemalloc.stop" title="tracemalloc.stop"><code class="xref py py-func docutils literal notranslate"><span class="pre">stop()</span></code></a>.</p>
</dd></dl>
<dl class="function">
<dt id="tracemalloc.get_object_traceback">
<code class="sig-prename descclassname">tracemalloc.</code><code class="sig-name descname">get_object_traceback</code><span class="sig-paren">(</span><em class="sig-param">obj</em><span class="sig-paren">)</span><a class="headerlink" href="#tracemalloc.get_object_traceback" title="Permalink to this definition">¶</a></dt>
<dd><p>Get the traceback where the Python object <em>obj</em> was allocated.
Return a <a class="reference internal" href="#tracemalloc.Traceback" title="tracemalloc.Traceback"><code class="xref py py-class docutils literal notranslate"><span class="pre">Traceback</span></code></a> instance, or <code class="docutils literal notranslate"><span class="pre">None</span></code> if the <a class="reference internal" href="#module-tracemalloc" title="tracemalloc: Trace memory allocations."><code class="xref py py-mod docutils literal notranslate"><span class="pre">tracemalloc</span></code></a>
module is not tracing memory allocations or did not trace the allocation of
the object.</p>
<p>See also <a class="reference internal" href="gc.html#gc.get_referrers" title="gc.get_referrers"><code class="xref py py-func docutils literal notranslate"><span class="pre">gc.get_referrers()</span></code></a> and <a class="reference internal" href="sys.html#sys.getsizeof" title="sys.getsizeof"><code class="xref py py-func docutils literal notranslate"><span class="pre">sys.getsizeof()</span></code></a> functions.</p>
</dd></dl>
<dl class="function">
<dt id="tracemalloc.get_traceback_limit">
<code class="sig-prename descclassname">tracemalloc.</code><code class="sig-name descname">get_traceback_limit</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#tracemalloc.get_traceback_limit" title="Permalink to this definition">¶</a></dt>
<dd><p>Get the maximum number of frames stored in the traceback of a trace.</p>
<p>The <a class="reference internal" href="#module-tracemalloc" title="tracemalloc: Trace memory allocations."><code class="xref py py-mod docutils literal notranslate"><span class="pre">tracemalloc</span></code></a> module must be tracing memory allocations to
get the limit, otherwise an exception is raised.</p>
<p>The limit is set by the <a class="reference internal" href="#tracemalloc.start" title="tracemalloc.start"><code class="xref py py-func docutils literal notranslate"><span class="pre">start()</span></code></a> function.</p>
</dd></dl>
<dl class="function">
<dt id="tracemalloc.get_traced_memory">
<code class="sig-prename descclassname">tracemalloc.</code><code class="sig-name descname">get_traced_memory</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#tracemalloc.get_traced_memory" title="Permalink to this definition">¶</a></dt>
<dd><p>Get the current size and peak size of memory blocks traced by the
<a class="reference internal" href="#module-tracemalloc" title="tracemalloc: Trace memory allocations."><code class="xref py py-mod docutils literal notranslate"><span class="pre">tracemalloc</span></code></a> module as a tuple: <code class="docutils literal notranslate"><span class="pre">(current:</span> <span class="pre">int,</span> <span class="pre">peak:</span> <span class="pre">int)</span></code>.</p>
</dd></dl>
<dl class="function">
<dt id="tracemalloc.get_tracemalloc_memory">
<code class="sig-prename descclassname">tracemalloc.</code><code class="sig-name descname">get_tracemalloc_memory</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#tracemalloc.get_tracemalloc_memory" title="Permalink to this definition">¶</a></dt>
<dd><p>Get the memory usage in bytes of the <a class="reference internal" href="#module-tracemalloc" title="tracemalloc: Trace memory allocations."><code class="xref py py-mod docutils literal notranslate"><span class="pre">tracemalloc</span></code></a> module used to store
traces of memory blocks.
Return an <a class="reference internal" href="functions.html#int" title="int"><code class="xref py py-class docutils literal notranslate"><span class="pre">int</span></code></a>.</p>
</dd></dl>
<dl class="function">
<dt id="tracemalloc.is_tracing">
<code class="sig-prename descclassname">tracemalloc.</code><code class="sig-name descname">is_tracing</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#tracemalloc.is_tracing" title="Permalink to this definition">¶</a></dt>
<dd><p><code class="docutils literal notranslate"><span class="pre">True</span></code> if the <a class="reference internal" href="#module-tracemalloc" title="tracemalloc: Trace memory allocations."><code class="xref py py-mod docutils literal notranslate"><span class="pre">tracemalloc</span></code></a> module is tracing Python memory
allocations, <code class="docutils literal notranslate"><span class="pre">False</span></code> otherwise.</p>
<p>See also <a class="reference internal" href="#tracemalloc.start" title="tracemalloc.start"><code class="xref py py-func docutils literal notranslate"><span class="pre">start()</span></code></a> and <a class="reference internal" href="#tracemalloc.stop" title="tracemalloc.stop"><code class="xref py py-func docutils literal notranslate"><span class="pre">stop()</span></code></a> functions.</p>
</dd></dl>
<dl class="function">
<dt id="tracemalloc.start">
<code class="sig-prename descclassname">tracemalloc.</code><code class="sig-name descname">start</code><span class="sig-paren">(</span><em class="sig-param">nframe: int=1</em><span class="sig-paren">)</span><a class="headerlink" href="#tracemalloc.start" title="Permalink to this definition">¶</a></dt>
<dd><p>Start tracing Python memory allocations: install hooks on Python memory
allocators. Collected tracebacks of traces will be limited to <em>nframe</em>
frames. By default, a trace of a memory block only stores the most recent
frame: the limit is <code class="docutils literal notranslate"><span class="pre">1</span></code>. <em>nframe</em> must be greater or equal to <code class="docutils literal notranslate"><span class="pre">1</span></code>.</p>
<p>Storing more than <code class="docutils literal notranslate"><span class="pre">1</span></code> frame is only useful to compute statistics grouped
by <code class="docutils literal notranslate"><span class="pre">'traceback'</span></code> or to compute cumulative statistics: see the
<a class="reference internal" href="#tracemalloc.Snapshot.compare_to" title="tracemalloc.Snapshot.compare_to"><code class="xref py py-meth docutils literal notranslate"><span class="pre">Snapshot.compare_to()</span></code></a> and <a class="reference internal" href="#tracemalloc.Snapshot.statistics" title="tracemalloc.Snapshot.statistics"><code class="xref py py-meth docutils literal notranslate"><span class="pre">Snapshot.statistics()</span></code></a> methods.</p>
<p>Storing more frames increases the memory and CPU overhead of the
<a class="reference internal" href="#module-tracemalloc" title="tracemalloc: Trace memory allocations."><code class="xref py py-mod docutils literal notranslate"><span class="pre">tracemalloc</span></code></a> module. Use the <a class="reference internal" href="#tracemalloc.get_tracemalloc_memory" title="tracemalloc.get_tracemalloc_memory"><code class="xref py py-func docutils literal notranslate"><span class="pre">get_tracemalloc_memory()</span></code></a> function
to measure how much memory is used by the <a class="reference internal" href="#module-tracemalloc" title="tracemalloc: Trace memory allocations."><code class="xref py py-mod docutils literal notranslate"><span class="pre">tracemalloc</span></code></a> module.</p>
<p>The <span class="target" id="index-2"></span><a class="reference internal" href="../using/cmdline.html#envvar-PYTHONTRACEMALLOC"><code class="xref std std-envvar docutils literal notranslate"><span class="pre">PYTHONTRACEMALLOC</span></code></a> environment variable
(<code class="docutils literal notranslate"><span class="pre">PYTHONTRACEMALLOC=NFRAME</span></code>) and the <a class="reference internal" href="../using/cmdline.html#id5"><code class="xref std std-option docutils literal notranslate"><span class="pre">-X</span></code></a> <code class="docutils literal notranslate"><span class="pre">tracemalloc=NFRAME</span></code>
command line option can be used to start tracing at startup.</p>
<p>See also <a class="reference internal" href="#tracemalloc.stop" title="tracemalloc.stop"><code class="xref py py-func docutils literal notranslate"><span class="pre">stop()</span></code></a>, <a class="reference internal" href="#tracemalloc.is_tracing" title="tracemalloc.is_tracing"><code class="xref py py-func docutils literal notranslate"><span class="pre">is_tracing()</span></code></a> and <a class="reference internal" href="#tracemalloc.get_traceback_limit" title="tracemalloc.get_traceback_limit"><code class="xref py py-func docutils literal notranslate"><span class="pre">get_traceback_limit()</span></code></a>
functions.</p>
</dd></dl>
<dl class="function">
<dt id="tracemalloc.stop">
<code class="sig-prename descclassname">tracemalloc.</code><code class="sig-name descname">stop</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#tracemalloc.stop" title="Permalink to this definition">¶</a></dt>
<dd><p>Stop tracing Python memory allocations: uninstall hooks on Python memory
allocators. Also clears all previously collected traces of memory blocks
allocated by Python.</p>
<p>Call <a class="reference internal" href="#tracemalloc.take_snapshot" title="tracemalloc.take_snapshot"><code class="xref py py-func docutils literal notranslate"><span class="pre">take_snapshot()</span></code></a> function to take a snapshot of traces before
clearing them.</p>
<p>See also <a class="reference internal" href="#tracemalloc.start" title="tracemalloc.start"><code class="xref py py-func docutils literal notranslate"><span class="pre">start()</span></code></a>, <a class="reference internal" href="#tracemalloc.is_tracing" title="tracemalloc.is_tracing"><code class="xref py py-func docutils literal notranslate"><span class="pre">is_tracing()</span></code></a> and <a class="reference internal" href="#tracemalloc.clear_traces" title="tracemalloc.clear_traces"><code class="xref py py-func docutils literal notranslate"><span class="pre">clear_traces()</span></code></a>
functions.</p>
</dd></dl>
<dl class="function">
<dt id="tracemalloc.take_snapshot">
<code class="sig-prename descclassname">tracemalloc.</code><code class="sig-name descname">take_snapshot</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#tracemalloc.take_snapshot" title="Permalink to this definition">¶</a></dt>
<dd><p>Take a snapshot of traces of memory blocks allocated by Python. Return a new
<a class="reference internal" href="#tracemalloc.Snapshot" title="tracemalloc.Snapshot"><code class="xref py py-class docutils literal notranslate"><span class="pre">Snapshot</span></code></a> instance.</p>
<p>The snapshot does not include memory blocks allocated before the
<a class="reference internal" href="#module-tracemalloc" title="tracemalloc: Trace memory allocations."><code class="xref py py-mod docutils literal notranslate"><span class="pre">tracemalloc</span></code></a> module started to trace memory allocations.</p>
<p>Tracebacks of traces are limited to <a class="reference internal" href="#tracemalloc.get_traceback_limit" title="tracemalloc.get_traceback_limit"><code class="xref py py-func docutils literal notranslate"><span class="pre">get_traceback_limit()</span></code></a> frames. Use
the <em>nframe</em> parameter of the <a class="reference internal" href="#tracemalloc.start" title="tracemalloc.start"><code class="xref py py-func docutils literal notranslate"><span class="pre">start()</span></code></a> function to store more frames.</p>
<p>The <a class="reference internal" href="#module-tracemalloc" title="tracemalloc: Trace memory allocations."><code class="xref py py-mod docutils literal notranslate"><span class="pre">tracemalloc</span></code></a> module must be tracing memory allocations to take a
snapshot, see the <a class="reference internal" href="#tracemalloc.start" title="tracemalloc.start"><code class="xref py py-func docutils literal notranslate"><span class="pre">start()</span></code></a> function.</p>
<p>See also the <a class="reference internal" href="#tracemalloc.get_object_traceback" title="tracemalloc.get_object_traceback"><code class="xref py py-func docutils literal notranslate"><span class="pre">get_object_traceback()</span></code></a> function.</p>
</dd></dl>
</div>
<div class="section" id="domainfilter">
<h3>DomainFilter<a class="headerlink" href="#domainfilter" title="Permalink to this headline">¶</a></h3>
<dl class="class">
<dt id="tracemalloc.DomainFilter">
<em class="property">class </em><code class="sig-prename descclassname">tracemalloc.</code><code class="sig-name descname">DomainFilter</code><span class="sig-paren">(</span><em class="sig-param">inclusive: bool</em>, <em class="sig-param">domain: int</em><span class="sig-paren">)</span><a class="headerlink" href="#tracemalloc.DomainFilter" title="Permalink to this definition">¶</a></dt>
<dd><p>Filter traces of memory blocks by their address space (domain).</p>
<div class="versionadded">
<p><span class="versionmodified added">New in version 3.6.</span></p>
</div>
<dl class="attribute">
<dt id="tracemalloc.DomainFilter.inclusive">
<code class="sig-name descname">inclusive</code><a class="headerlink" href="#tracemalloc.DomainFilter.inclusive" title="Permalink to this definition">¶</a></dt>
<dd><p>If <em>inclusive</em> is <code class="docutils literal notranslate"><span class="pre">True</span></code> (include), match memory blocks allocated
in the address space <a class="reference internal" href="#tracemalloc.DomainFilter.domain" title="tracemalloc.DomainFilter.domain"><code class="xref py py-attr docutils literal notranslate"><span class="pre">domain</span></code></a>.</p>
<p>If <em>inclusive</em> is <code class="docutils literal notranslate"><span class="pre">False</span></code> (exclude), match memory blocks not allocated
in the address space <a class="reference internal" href="#tracemalloc.DomainFilter.domain" title="tracemalloc.DomainFilter.domain"><code class="xref py py-attr docutils literal notranslate"><span class="pre">domain</span></code></a>.</p>
</dd></dl>
<dl class="attribute">
<dt id="tracemalloc.DomainFilter.domain">
<code class="sig-name descname">domain</code><a class="headerlink" href="#tracemalloc.DomainFilter.domain" title="Permalink to this definition">¶</a></dt>
<dd><p>Address space of a memory block (<code class="docutils literal notranslate"><span class="pre">int</span></code>). Read-only property.</p>
</dd></dl>
</dd></dl>
</div>
<div class="section" id="filter">
<h3>Filter<a class="headerlink" href="#filter" title="Permalink to this headline">¶</a></h3>
<dl class="class">
<dt id="tracemalloc.Filter">
<em class="property">class </em><code class="sig-prename descclassname">tracemalloc.</code><code class="sig-name descname">Filter</code><span class="sig-paren">(</span><em class="sig-param">inclusive: bool</em>, <em class="sig-param">filename_pattern: str</em>, <em class="sig-param">lineno: int=None</em>, <em class="sig-param">all_frames: bool=False</em>, <em class="sig-param">domain: int=None</em><span class="sig-paren">)</span><a class="headerlink" href="#tracemalloc.Filter" title="Permalink to this definition">¶</a></dt>
<dd><p>Filter on traces of memory blocks.</p>
<p>See the <a class="reference internal" href="fnmatch.html#fnmatch.fnmatch" title="fnmatch.fnmatch"><code class="xref py py-func docutils literal notranslate"><span class="pre">fnmatch.fnmatch()</span></code></a> function for the syntax of
<em>filename_pattern</em>. The <code class="docutils literal notranslate"><span class="pre">'.pyc'</span></code> file extension is
replaced with <code class="docutils literal notranslate"><span class="pre">'.py'</span></code>.</p>
<p>Examples:</p>
<ul class="simple">
<li><p><code class="docutils literal notranslate"><span class="pre">Filter(True,</span> <span class="pre">subprocess.__file__)</span></code> only includes traces of the
<a class="reference internal" href="subprocess.html#module-subprocess" title="subprocess: Subprocess management."><code class="xref py py-mod docutils literal notranslate"><span class="pre">subprocess</span></code></a> module</p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">Filter(False,</span> <span class="pre">tracemalloc.__file__)</span></code> excludes traces of the
<a class="reference internal" href="#module-tracemalloc" title="tracemalloc: Trace memory allocations."><code class="xref py py-mod docutils literal notranslate"><span class="pre">tracemalloc</span></code></a> module</p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">Filter(False,</span> <span class="pre">"<unknown>")</span></code> excludes empty tracebacks</p></li>
</ul>
<div class="versionchanged">
<p><span class="versionmodified changed">Changed in version 3.5: </span>The <code class="docutils literal notranslate"><span class="pre">'.pyo'</span></code> file extension is no longer replaced with <code class="docutils literal notranslate"><span class="pre">'.py'</span></code>.</p>
</div>
<div class="versionchanged">
<p><span class="versionmodified changed">Changed in version 3.6: </span>Added the <a class="reference internal" href="#tracemalloc.Filter.domain" title="tracemalloc.Filter.domain"><code class="xref py py-attr docutils literal notranslate"><span class="pre">domain</span></code></a> attribute.</p>
</div>
<dl class="attribute">
<dt id="tracemalloc.Filter.domain">
<code class="sig-name descname">domain</code><a class="headerlink" href="#tracemalloc.Filter.domain" title="Permalink to this definition">¶</a></dt>
<dd><p>Address space of a memory block (<code class="docutils literal notranslate"><span class="pre">int</span></code> or <code class="docutils literal notranslate"><span class="pre">None</span></code>).</p>
<p>tracemalloc uses the domain <code class="docutils literal notranslate"><span class="pre">0</span></code> to trace memory allocations made by
Python. C extensions can use other domains to trace other resources.</p>
</dd></dl>
<dl class="attribute">
<dt id="tracemalloc.Filter.inclusive">
<code class="sig-name descname">inclusive</code><a class="headerlink" href="#tracemalloc.Filter.inclusive" title="Permalink to this definition">¶</a></dt>
<dd><p>If <em>inclusive</em> is <code class="docutils literal notranslate"><span class="pre">True</span></code> (include), only match memory blocks allocated
in a file with a name matching <a class="reference internal" href="#tracemalloc.Filter.filename_pattern" title="tracemalloc.Filter.filename_pattern"><code class="xref py py-attr docutils literal notranslate"><span class="pre">filename_pattern</span></code></a> at line number
<a class="reference internal" href="#tracemalloc.Filter.lineno" title="tracemalloc.Filter.lineno"><code class="xref py py-attr docutils literal notranslate"><span class="pre">lineno</span></code></a>.</p>
<p>If <em>inclusive</em> is <code class="docutils literal notranslate"><span class="pre">False</span></code> (exclude), ignore memory blocks allocated in
a file with a name matching <a class="reference internal" href="#tracemalloc.Filter.filename_pattern" title="tracemalloc.Filter.filename_pattern"><code class="xref py py-attr docutils literal notranslate"><span class="pre">filename_pattern</span></code></a> at line number
<a class="reference internal" href="#tracemalloc.Filter.lineno" title="tracemalloc.Filter.lineno"><code class="xref py py-attr docutils literal notranslate"><span class="pre">lineno</span></code></a>.</p>
</dd></dl>
<dl class="attribute">
<dt id="tracemalloc.Filter.lineno">
<code class="sig-name descname">lineno</code><a class="headerlink" href="#tracemalloc.Filter.lineno" title="Permalink to this definition">¶</a></dt>
<dd><p>Line number (<code class="docutils literal notranslate"><span class="pre">int</span></code>) of the filter. If <em>lineno</em> is <code class="docutils literal notranslate"><span class="pre">None</span></code>, the filter
matches any line number.</p>
</dd></dl>
<dl class="attribute">
<dt id="tracemalloc.Filter.filename_pattern">
<code class="sig-name descname">filename_pattern</code><a class="headerlink" href="#tracemalloc.Filter.filename_pattern" title="Permalink to this definition">¶</a></dt>
<dd><p>Filename pattern of the filter (<code class="docutils literal notranslate"><span class="pre">str</span></code>). Read-only property.</p>
</dd></dl>
<dl class="attribute">
<dt id="tracemalloc.Filter.all_frames">
<code class="sig-name descname">all_frames</code><a class="headerlink" href="#tracemalloc.Filter.all_frames" title="Permalink to this definition">¶</a></dt>
<dd><p>If <em>all_frames</em> is <code class="docutils literal notranslate"><span class="pre">True</span></code>, all frames of the traceback are checked. If
<em>all_frames</em> is <code class="docutils literal notranslate"><span class="pre">False</span></code>, only the most recent frame is checked.</p>
<p>This attribute has no effect if the traceback limit is <code class="docutils literal notranslate"><span class="pre">1</span></code>. See the
<a class="reference internal" href="#tracemalloc.get_traceback_limit" title="tracemalloc.get_traceback_limit"><code class="xref py py-func docutils literal notranslate"><span class="pre">get_traceback_limit()</span></code></a> function and <a class="reference internal" href="#tracemalloc.Snapshot.traceback_limit" title="tracemalloc.Snapshot.traceback_limit"><code class="xref py py-attr docutils literal notranslate"><span class="pre">Snapshot.traceback_limit</span></code></a>
attribute.</p>
</dd></dl>
</dd></dl>
</div>
<div class="section" id="frame">
<h3>Frame<a class="headerlink" href="#frame" title="Permalink to this headline">¶</a></h3>
<dl class="class">
<dt id="tracemalloc.Frame">
<em class="property">class </em><code class="sig-prename descclassname">tracemalloc.</code><code class="sig-name descname">Frame</code><a class="headerlink" href="#tracemalloc.Frame" title="Permalink to this definition">¶</a></dt>
<dd><p>Frame of a traceback.</p>
<p>The <a class="reference internal" href="#tracemalloc.Traceback" title="tracemalloc.Traceback"><code class="xref py py-class docutils literal notranslate"><span class="pre">Traceback</span></code></a> class is a sequence of <a class="reference internal" href="#tracemalloc.Frame" title="tracemalloc.Frame"><code class="xref py py-class docutils literal notranslate"><span class="pre">Frame</span></code></a> instances.</p>
<dl class="attribute">
<dt id="tracemalloc.Frame.filename">
<code class="sig-name descname">filename</code><a class="headerlink" href="#tracemalloc.Frame.filename" title="Permalink to this definition">¶</a></dt>
<dd><p>Filename (<code class="docutils literal notranslate"><span class="pre">str</span></code>).</p>
</dd></dl>
<dl class="attribute">
<dt id="tracemalloc.Frame.lineno">
<code class="sig-name descname">lineno</code><a class="headerlink" href="#tracemalloc.Frame.lineno" title="Permalink to this definition">¶</a></dt>
<dd><p>Line number (<code class="docutils literal notranslate"><span class="pre">int</span></code>).</p>
</dd></dl>
</dd></dl>
</div>
<div class="section" id="snapshot">
<h3>Snapshot<a class="headerlink" href="#snapshot" title="Permalink to this headline">¶</a></h3>
<dl class="class">
<dt id="tracemalloc.Snapshot">
<em class="property">class </em><code class="sig-prename descclassname">tracemalloc.</code><code class="sig-name descname">Snapshot</code><a class="headerlink" href="#tracemalloc.Snapshot" title="Permalink to this definition">¶</a></dt>
<dd><p>Snapshot of traces of memory blocks allocated by Python.</p>
<p>The <a class="reference internal" href="#tracemalloc.take_snapshot" title="tracemalloc.take_snapshot"><code class="xref py py-func docutils literal notranslate"><span class="pre">take_snapshot()</span></code></a> function creates a snapshot instance.</p>
<dl class="method">
<dt id="tracemalloc.Snapshot.compare_to">
<code class="sig-name descname">compare_to</code><span class="sig-paren">(</span><em class="sig-param">old_snapshot: Snapshot</em>, <em class="sig-param">key_type: str</em>, <em class="sig-param">cumulative: bool=False</em><span class="sig-paren">)</span><a class="headerlink" href="#tracemalloc.Snapshot.compare_to" title="Permalink to this definition">¶</a></dt>
<dd><p>Compute the differences with an old snapshot. Get statistics as a sorted
list of <a class="reference internal" href="#tracemalloc.StatisticDiff" title="tracemalloc.StatisticDiff"><code class="xref py py-class docutils literal notranslate"><span class="pre">StatisticDiff</span></code></a> instances grouped by <em>key_type</em>.</p>
<p>See the <a class="reference internal" href="#tracemalloc.Snapshot.statistics" title="tracemalloc.Snapshot.statistics"><code class="xref py py-meth docutils literal notranslate"><span class="pre">Snapshot.statistics()</span></code></a> method for <em>key_type</em> and <em>cumulative</em>
parameters.</p>
<p>The result is sorted from the biggest to the smallest by: absolute value
of <a class="reference internal" href="#tracemalloc.StatisticDiff.size_diff" title="tracemalloc.StatisticDiff.size_diff"><code class="xref py py-attr docutils literal notranslate"><span class="pre">StatisticDiff.size_diff</span></code></a>, <a class="reference internal" href="#tracemalloc.StatisticDiff.size" title="tracemalloc.StatisticDiff.size"><code class="xref py py-attr docutils literal notranslate"><span class="pre">StatisticDiff.size</span></code></a>, absolute
value of <a class="reference internal" href="#tracemalloc.StatisticDiff.count_diff" title="tracemalloc.StatisticDiff.count_diff"><code class="xref py py-attr docutils literal notranslate"><span class="pre">StatisticDiff.count_diff</span></code></a>, <a class="reference internal" href="#tracemalloc.Statistic.count" title="tracemalloc.Statistic.count"><code class="xref py py-attr docutils literal notranslate"><span class="pre">Statistic.count</span></code></a> and
then by <a class="reference internal" href="#tracemalloc.StatisticDiff.traceback" title="tracemalloc.StatisticDiff.traceback"><code class="xref py py-attr docutils literal notranslate"><span class="pre">StatisticDiff.traceback</span></code></a>.</p>
</dd></dl>
<dl class="method">
<dt id="tracemalloc.Snapshot.dump">
<code class="sig-name descname">dump</code><span class="sig-paren">(</span><em class="sig-param">filename</em><span class="sig-paren">)</span><a class="headerlink" href="#tracemalloc.Snapshot.dump" title="Permalink to this definition">¶</a></dt>
<dd><p>Write the snapshot into a file.</p>
<p>Use <a class="reference internal" href="#tracemalloc.Snapshot.load" title="tracemalloc.Snapshot.load"><code class="xref py py-meth docutils literal notranslate"><span class="pre">load()</span></code></a> to reload the snapshot.</p>
</dd></dl>
<dl class="method">
<dt id="tracemalloc.Snapshot.filter_traces">
<code class="sig-name descname">filter_traces</code><span class="sig-paren">(</span><em class="sig-param">filters</em><span class="sig-paren">)</span><a class="headerlink" href="#tracemalloc.Snapshot.filter_traces" title="Permalink to this definition">¶</a></dt>
<dd><p>Create a new <a class="reference internal" href="#tracemalloc.Snapshot" title="tracemalloc.Snapshot"><code class="xref py py-class docutils literal notranslate"><span class="pre">Snapshot</span></code></a> instance with a filtered <a class="reference internal" href="#tracemalloc.Snapshot.traces" title="tracemalloc.Snapshot.traces"><code class="xref py py-attr docutils literal notranslate"><span class="pre">traces</span></code></a>
sequence, <em>filters</em> is a list of <a class="reference internal" href="#tracemalloc.DomainFilter" title="tracemalloc.DomainFilter"><code class="xref py py-class docutils literal notranslate"><span class="pre">DomainFilter</span></code></a> and
<a class="reference internal" href="#tracemalloc.Filter" title="tracemalloc.Filter"><code class="xref py py-class docutils literal notranslate"><span class="pre">Filter</span></code></a> instances. If <em>filters</em> is an empty list, return a new
<a class="reference internal" href="#tracemalloc.Snapshot" title="tracemalloc.Snapshot"><code class="xref py py-class docutils literal notranslate"><span class="pre">Snapshot</span></code></a> instance with a copy of the traces.</p>
<p>All inclusive filters are applied at once, a trace is ignored if no
inclusive filters match it. A trace is ignored if at least one exclusive
filter matches it.</p>
<div class="versionchanged">
<p><span class="versionmodified changed">Changed in version 3.6: </span><a class="reference internal" href="#tracemalloc.DomainFilter" title="tracemalloc.DomainFilter"><code class="xref py py-class docutils literal notranslate"><span class="pre">DomainFilter</span></code></a> instances are now also accepted in <em>filters</em>.</p>
</div>
</dd></dl>
<dl class="method">
<dt id="tracemalloc.Snapshot.load">
<em class="property">classmethod </em><code class="sig-name descname">load</code><span class="sig-paren">(</span><em class="sig-param">filename</em><span class="sig-paren">)</span><a class="headerlink" href="#tracemalloc.Snapshot.load" title="Permalink to this definition">¶</a></dt>
<dd><p>Load a snapshot from a file.</p>
<p>See also <a class="reference internal" href="#tracemalloc.Snapshot.dump" title="tracemalloc.Snapshot.dump"><code class="xref py py-meth docutils literal notranslate"><span class="pre">dump()</span></code></a>.</p>
</dd></dl>
<dl class="method">
<dt id="tracemalloc.Snapshot.statistics">
<code class="sig-name descname">statistics</code><span class="sig-paren">(</span><em class="sig-param">key_type: str</em>, <em class="sig-param">cumulative: bool=False</em><span class="sig-paren">)</span><a class="headerlink" href="#tracemalloc.Snapshot.statistics" title="Permalink to this definition">¶</a></dt>
<dd><p>Get statistics as a sorted list of <a class="reference internal" href="#tracemalloc.Statistic" title="tracemalloc.Statistic"><code class="xref py py-class docutils literal notranslate"><span class="pre">Statistic</span></code></a> instances grouped
by <em>key_type</em>:</p>
<table class="docutils align-default">
<colgroup>
<col style="width: 47%" />
<col style="width: 53%" />
</colgroup>
<thead>
<tr class="row-odd"><th class="head"><p>key_type</p></th>
<th class="head"><p>description</p></th>
</tr>
</thead>
<tbody>
<tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">'filename'</span></code></p></td>
<td><p>filename</p></td>
</tr>
<tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">'lineno'</span></code></p></td>
<td><p>filename and line number</p></td>
</tr>
<tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">'traceback'</span></code></p></td>
<td><p>traceback</p></td>
</tr>
</tbody>
</table>
<p>If <em>cumulative</em> is <code class="docutils literal notranslate"><span class="pre">True</span></code>, cumulate size and count of memory blocks of
all frames of the traceback of a trace, not only the most recent frame.
The cumulative mode can only be used with <em>key_type</em> equals to
<code class="docutils literal notranslate"><span class="pre">'filename'</span></code> and <code class="docutils literal notranslate"><span class="pre">'lineno'</span></code>.</p>
<p>The result is sorted from the biggest to the smallest by:
<a class="reference internal" href="#tracemalloc.Statistic.size" title="tracemalloc.Statistic.size"><code class="xref py py-attr docutils literal notranslate"><span class="pre">Statistic.size</span></code></a>, <a class="reference internal" href="#tracemalloc.Statistic.count" title="tracemalloc.Statistic.count"><code class="xref py py-attr docutils literal notranslate"><span class="pre">Statistic.count</span></code></a> and then by
<a class="reference internal" href="#tracemalloc.Statistic.traceback" title="tracemalloc.Statistic.traceback"><code class="xref py py-attr docutils literal notranslate"><span class="pre">Statistic.traceback</span></code></a>.</p>
</dd></dl>
<dl class="attribute">
<dt id="tracemalloc.Snapshot.traceback_limit">
<code class="sig-name descname">traceback_limit</code><a class="headerlink" href="#tracemalloc.Snapshot.traceback_limit" title="Permalink to this definition">¶</a></dt>
<dd><p>Maximum number of frames stored in the traceback of <a class="reference internal" href="#tracemalloc.Snapshot.traces" title="tracemalloc.Snapshot.traces"><code class="xref py py-attr docutils literal notranslate"><span class="pre">traces</span></code></a>:
result of the <a class="reference internal" href="#tracemalloc.get_traceback_limit" title="tracemalloc.get_traceback_limit"><code class="xref py py-func docutils literal notranslate"><span class="pre">get_traceback_limit()</span></code></a> when the snapshot was taken.</p>
</dd></dl>
<dl class="attribute">
<dt id="tracemalloc.Snapshot.traces">
<code class="sig-name descname">traces</code><a class="headerlink" href="#tracemalloc.Snapshot.traces" title="Permalink to this definition">¶</a></dt>
<dd><p>Traces of all memory blocks allocated by Python: sequence of
<a class="reference internal" href="#tracemalloc.Trace" title="tracemalloc.Trace"><code class="xref py py-class docutils literal notranslate"><span class="pre">Trace</span></code></a> instances.</p>
<p>The sequence has an undefined order. Use the <a class="reference internal" href="#tracemalloc.Snapshot.statistics" title="tracemalloc.Snapshot.statistics"><code class="xref py py-meth docutils literal notranslate"><span class="pre">Snapshot.statistics()</span></code></a>
method to get a sorted list of statistics.</p>
</dd></dl>
</dd></dl>
</div>
<div class="section" id="statistic">
<h3>Statistic<a class="headerlink" href="#statistic" title="Permalink to this headline">¶</a></h3>
<dl class="class">
<dt id="tracemalloc.Statistic">
<em class="property">class </em><code class="sig-prename descclassname">tracemalloc.</code><code class="sig-name descname">Statistic</code><a class="headerlink" href="#tracemalloc.Statistic" title="Permalink to this definition">¶</a></dt>
<dd><p>Statistic on memory allocations.</p>
<p><a class="reference internal" href="#tracemalloc.Snapshot.statistics" title="tracemalloc.Snapshot.statistics"><code class="xref py py-func docutils literal notranslate"><span class="pre">Snapshot.statistics()</span></code></a> returns a list of <a class="reference internal" href="#tracemalloc.Statistic" title="tracemalloc.Statistic"><code class="xref py py-class docutils literal notranslate"><span class="pre">Statistic</span></code></a> instances.</p>
<p>See also the <a class="reference internal" href="#tracemalloc.StatisticDiff" title="tracemalloc.StatisticDiff"><code class="xref py py-class docutils literal notranslate"><span class="pre">StatisticDiff</span></code></a> class.</p>
<dl class="attribute">
<dt id="tracemalloc.Statistic.count">
<code class="sig-name descname">count</code><a class="headerlink" href="#tracemalloc.Statistic.count" title="Permalink to this definition">¶</a></dt>
<dd><p>Number of memory blocks (<code class="docutils literal notranslate"><span class="pre">int</span></code>).</p>
</dd></dl>
<dl class="attribute">
<dt id="tracemalloc.Statistic.size">
<code class="sig-name descname">size</code><a class="headerlink" href="#tracemalloc.Statistic.size" title="Permalink to this definition">¶</a></dt>
<dd><p>Total size of memory blocks in bytes (<code class="docutils literal notranslate"><span class="pre">int</span></code>).</p>
</dd></dl>
<dl class="attribute">
<dt id="tracemalloc.Statistic.traceback">
<code class="sig-name descname">traceback</code><a class="headerlink" href="#tracemalloc.Statistic.traceback" title="Permalink to this definition">¶</a></dt>
<dd><p>Traceback where the memory block was allocated, <a class="reference internal" href="#tracemalloc.Traceback" title="tracemalloc.Traceback"><code class="xref py py-class docutils literal notranslate"><span class="pre">Traceback</span></code></a>
instance.</p>
</dd></dl>
</dd></dl>
</div>
<div class="section" id="statisticdiff">
<h3>StatisticDiff<a class="headerlink" href="#statisticdiff" title="Permalink to this headline">¶</a></h3>
<dl class="class">
<dt id="tracemalloc.StatisticDiff">
<em class="property">class </em><code class="sig-prename descclassname">tracemalloc.</code><code class="sig-name descname">StatisticDiff</code><a class="headerlink" href="#tracemalloc.StatisticDiff" title="Permalink to this definition">¶</a></dt>
<dd><p>Statistic difference on memory allocations between an old and a new
<a class="reference internal" href="#tracemalloc.Snapshot" title="tracemalloc.Snapshot"><code class="xref py py-class docutils literal notranslate"><span class="pre">Snapshot</span></code></a> instance.</p>
<p><a class="reference internal" href="#tracemalloc.Snapshot.compare_to" title="tracemalloc.Snapshot.compare_to"><code class="xref py py-func docutils literal notranslate"><span class="pre">Snapshot.compare_to()</span></code></a> returns a list of <a class="reference internal" href="#tracemalloc.StatisticDiff" title="tracemalloc.StatisticDiff"><code class="xref py py-class docutils literal notranslate"><span class="pre">StatisticDiff</span></code></a>
instances. See also the <a class="reference internal" href="#tracemalloc.Statistic" title="tracemalloc.Statistic"><code class="xref py py-class docutils literal notranslate"><span class="pre">Statistic</span></code></a> class.</p>
<dl class="attribute">
<dt id="tracemalloc.StatisticDiff.count">
<code class="sig-name descname">count</code><a class="headerlink" href="#tracemalloc.StatisticDiff.count" title="Permalink to this definition">¶</a></dt>
<dd><p>Number of memory blocks in the new snapshot (<code class="docutils literal notranslate"><span class="pre">int</span></code>): <code class="docutils literal notranslate"><span class="pre">0</span></code> if
the memory blocks have been released in the new snapshot.</p>
</dd></dl>
<dl class="attribute">
<dt id="tracemalloc.StatisticDiff.count_diff">
<code class="sig-name descname">count_diff</code><a class="headerlink" href="#tracemalloc.StatisticDiff.count_diff" title="Permalink to this definition">¶</a></dt>
<dd><p>Difference of number of memory blocks between the old and the new
snapshots (<code class="docutils literal notranslate"><span class="pre">int</span></code>): <code class="docutils literal notranslate"><span class="pre">0</span></code> if the memory blocks have been allocated in
the new snapshot.</p>
</dd></dl>
<dl class="attribute">
<dt id="tracemalloc.StatisticDiff.size">
<code class="sig-name descname">size</code><a class="headerlink" href="#tracemalloc.StatisticDiff.size" title="Permalink to this definition">¶</a></dt>
<dd><p>Total size of memory blocks in bytes in the new snapshot (<code class="docutils literal notranslate"><span class="pre">int</span></code>):
<code class="docutils literal notranslate"><span class="pre">0</span></code> if the memory blocks have been released in the new snapshot.</p>
</dd></dl>
<dl class="attribute">
<dt id="tracemalloc.StatisticDiff.size_diff">
<code class="sig-name descname">size_diff</code><a class="headerlink" href="#tracemalloc.StatisticDiff.size_diff" title="Permalink to this definition">¶</a></dt>
<dd><p>Difference of total size of memory blocks in bytes between the old and
the new snapshots (<code class="docutils literal notranslate"><span class="pre">int</span></code>): <code class="docutils literal notranslate"><span class="pre">0</span></code> if the memory blocks have been
allocated in the new snapshot.</p>
</dd></dl>
<dl class="attribute">
<dt id="tracemalloc.StatisticDiff.traceback">
<code class="sig-name descname">traceback</code><a class="headerlink" href="#tracemalloc.StatisticDiff.traceback" title="Permalink to this definition">¶</a></dt>
<dd><p>Traceback where the memory blocks were allocated, <a class="reference internal" href="#tracemalloc.Traceback" title="tracemalloc.Traceback"><code class="xref py py-class docutils literal notranslate"><span class="pre">Traceback</span></code></a>
instance.</p>
</dd></dl>
</dd></dl>
</div>
<div class="section" id="trace">
<h3>Trace<a class="headerlink" href="#trace" title="Permalink to this headline">¶</a></h3>
<dl class="class">
<dt id="tracemalloc.Trace">
<em class="property">class </em><code class="sig-prename descclassname">tracemalloc.</code><code class="sig-name descname">Trace</code><a class="headerlink" href="#tracemalloc.Trace" title="Permalink to this definition">¶</a></dt>
<dd><p>Trace of a memory block.</p>
<p>The <a class="reference internal" href="#tracemalloc.Snapshot.traces" title="tracemalloc.Snapshot.traces"><code class="xref py py-attr docutils literal notranslate"><span class="pre">Snapshot.traces</span></code></a> attribute is a sequence of <a class="reference internal" href="#tracemalloc.Trace" title="tracemalloc.Trace"><code class="xref py py-class docutils literal notranslate"><span class="pre">Trace</span></code></a>
instances.</p>
<div class="versionchanged">
<p><span class="versionmodified changed">Changed in version 3.6: </span>Added the <a class="reference internal" href="#tracemalloc.Trace.domain" title="tracemalloc.Trace.domain"><code class="xref py py-attr docutils literal notranslate"><span class="pre">domain</span></code></a> attribute.</p>
</div>
<dl class="attribute">
<dt id="tracemalloc.Trace.domain">
<code class="sig-name descname">domain</code><a class="headerlink" href="#tracemalloc.Trace.domain" title="Permalink to this definition">¶</a></dt>
<dd><p>Address space of a memory block (<code class="docutils literal notranslate"><span class="pre">int</span></code>). Read-only property.</p>
<p>tracemalloc uses the domain <code class="docutils literal notranslate"><span class="pre">0</span></code> to trace memory allocations made by
Python. C extensions can use other domains to trace other resources.</p>
</dd></dl>
<dl class="attribute">
<dt id="tracemalloc.Trace.size">
<code class="sig-name descname">size</code><a class="headerlink" href="#tracemalloc.Trace.size" title="Permalink to this definition">¶</a></dt>
<dd><p>Size of the memory block in bytes (<code class="docutils literal notranslate"><span class="pre">int</span></code>).</p>
</dd></dl>
<dl class="attribute">
<dt id="tracemalloc.Trace.traceback">
<code class="sig-name descname">traceback</code><a class="headerlink" href="#tracemalloc.Trace.traceback" title="Permalink to this definition">¶</a></dt>
<dd><p>Traceback where the memory block was allocated, <a class="reference internal" href="#tracemalloc.Traceback" title="tracemalloc.Traceback"><code class="xref py py-class docutils literal notranslate"><span class="pre">Traceback</span></code></a>
instance.</p>
</dd></dl>
</dd></dl>
</div>
<div class="section" id="traceback">
<h3>Traceback<a class="headerlink" href="#traceback" title="Permalink to this headline">¶</a></h3>
<dl class="class">
<dt id="tracemalloc.Traceback">
<em class="property">class </em><code class="sig-prename descclassname">tracemalloc.</code><code class="sig-name descname">Traceback</code><a class="headerlink" href="#tracemalloc.Traceback" title="Permalink to this definition">¶</a></dt>
<dd><p>Sequence of <a class="reference internal" href="#tracemalloc.Frame" title="tracemalloc.Frame"><code class="xref py py-class docutils literal notranslate"><span class="pre">Frame</span></code></a> instances sorted from the oldest frame to the
most recent frame.</p>
<p>A traceback contains at least <code class="docutils literal notranslate"><span class="pre">1</span></code> frame. If the <code class="docutils literal notranslate"><span class="pre">tracemalloc</span></code> module
failed to get a frame, the filename <code class="docutils literal notranslate"><span class="pre">"<unknown>"</span></code> at line number <code class="docutils literal notranslate"><span class="pre">0</span></code> is
used.</p>
<p>When a snapshot is taken, tracebacks of traces are limited to
<a class="reference internal" href="#tracemalloc.get_traceback_limit" title="tracemalloc.get_traceback_limit"><code class="xref py py-func docutils literal notranslate"><span class="pre">get_traceback_limit()</span></code></a> frames. See the <a class="reference internal" href="#tracemalloc.take_snapshot" title="tracemalloc.take_snapshot"><code class="xref py py-func docutils literal notranslate"><span class="pre">take_snapshot()</span></code></a> function.</p>
<p>The <a class="reference internal" href="#tracemalloc.Trace.traceback" title="tracemalloc.Trace.traceback"><code class="xref py py-attr docutils literal notranslate"><span class="pre">Trace.traceback</span></code></a> attribute is an instance of <a class="reference internal" href="#tracemalloc.Traceback" title="tracemalloc.Traceback"><code class="xref py py-class docutils literal notranslate"><span class="pre">Traceback</span></code></a>
instance.</p>
<div class="versionchanged">
<p><span class="versionmodified changed">Changed in version 3.7: </span>Frames are now sorted from the oldest to the most recent, instead of most recent to oldest.</p>
</div>
<dl class="method">
<dt id="tracemalloc.Traceback.format">
<code class="sig-name descname">format</code><span class="sig-paren">(</span><em class="sig-param">limit=None</em>, <em class="sig-param">most_recent_first=False</em><span class="sig-paren">)</span><a class="headerlink" href="#tracemalloc.Traceback.format" title="Permalink to this definition">¶</a></dt>
<dd><p>Format the traceback as a list of lines with newlines. Use the
<a class="reference internal" href="linecache.html#module-linecache" title="linecache: Provides random access to individual lines from text files."><code class="xref py py-mod docutils literal notranslate"><span class="pre">linecache</span></code></a> module to retrieve lines from the source code.
If <em>limit</em> is set, format the <em>limit</em> most recent frames if <em>limit</em>
is positive. Otherwise, format the <code class="docutils literal notranslate"><span class="pre">abs(limit)</span></code> oldest frames.
If <em>most_recent_first</em> is <code class="docutils literal notranslate"><span class="pre">True</span></code>, the order of the formatted frames
is reversed, returning the most recent frame first instead of last.</p>
<p>Similar to the <a class="reference internal" href="traceback.html#traceback.format_tb" title="traceback.format_tb"><code class="xref py py-func docutils literal notranslate"><span class="pre">traceback.format_tb()</span></code></a> function, except that
<a class="reference internal" href="#tracemalloc.Traceback.format" title="tracemalloc.Traceback.format"><code class="xref py py-meth docutils literal notranslate"><span class="pre">format()</span></code></a> does not include newlines.</p>
<p>Example:</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="nb">print</span><span class="p">(</span><span class="s2">"Traceback (most recent call first):"</span><span class="p">)</span>
<span class="k">for</span> <span class="n">line</span> <span class="ow">in</span> <span class="n">traceback</span><span class="p">:</span>
<span class="nb">print</span><span class="p">(</span><span class="n">line</span><span class="p">)</span>
</pre></div>
</div>
<p>Output:</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="n">Traceback</span> <span class="p">(</span><span class="n">most</span> <span class="n">recent</span> <span class="n">call</span> <span class="n">first</span><span class="p">):</span>
<span class="n">File</span> <span class="s2">"test.py"</span><span class="p">,</span> <span class="n">line</span> <span class="mi">9</span>
<span class="n">obj</span> <span class="o">=</span> <span class="n">Object</span><span class="p">()</span>
<span class="n">File</span> <span class="s2">"test.py"</span><span class="p">,</span> <span class="n">line</span> <span class="mi">12</span>
<span class="n">tb</span> <span class="o">=</span> <span class="n">tracemalloc</span><span class="o">.</span><span class="n">get_object_traceback</span><span class="p">(</span><span class="n">f</span><span class="p">())</span>
</pre></div>
</div>
</dd></dl>
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<ul>
<li><a class="reference internal" href="#"><code class="xref py py-mod docutils literal notranslate"><span class="pre">tracemalloc</span></code> — Trace memory allocations</a><ul>
<li><a class="reference internal" href="#examples">Examples</a><ul>
<li><a class="reference internal" href="#display-the-top-10">Display the top 10</a></li>
<li><a class="reference internal" href="#compute-differences">Compute differences</a></li>
<li><a class="reference internal" href="#get-the-traceback-of-a-memory-block">Get the traceback of a memory block</a></li>
<li><a class="reference internal" href="#pretty-top">Pretty top</a></li>
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<li><a class="reference internal" href="#api">API</a><ul>
<li><a class="reference internal" href="#functions">Functions</a></li>
<li><a class="reference internal" href="#domainfilter">DomainFilter</a></li>
<li><a class="reference internal" href="#filter">Filter</a></li>
<li><a class="reference internal" href="#frame">Frame</a></li>
<li><a class="reference internal" href="#snapshot">Snapshot</a></li>
<li><a class="reference internal" href="#statistic">Statistic</a></li>
<li><a class="reference internal" href="#statisticdiff">StatisticDiff</a></li>
<li><a class="reference internal" href="#trace">Trace</a></li>
<li><a class="reference internal" href="#traceback">Traceback</a></li>
</ul>
</li>
</ul>
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