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<ul>
<li><a class="reference internal" href="#"><code class="xref py py-mod docutils literal notranslate"><span class="pre">concurrent.interpreters</span></code> — Multiple interpreters in the same process</a><ul>
<li><a class="reference internal" href="#key-details">Key details</a></li>
<li><a class="reference internal" href="#introduction">Introduction</a><ul>
<li><a class="reference internal" href="#multiple-interpreters-and-isolation">Multiple Interpreters and Isolation</a></li>
<li><a class="reference internal" href="#running-in-an-interpreter">Running in an Interpreter</a></li>
<li><a class="reference internal" href="#concurrency-and-parallelism">Concurrency and Parallelism</a></li>
<li><a class="reference internal" href="#communication-between-interpreters">Communication Between Interpreters</a></li>
<li><a class="reference internal" href="#sharing-objects">“Sharing” Objects</a></li>
</ul>
</li>
<li><a class="reference internal" href="#reference">Reference</a><ul>
<li><a class="reference internal" href="#interpreter-objects">Interpreter objects</a></li>
<li><a class="reference internal" href="#exceptions">Exceptions</a></li>
<li><a class="reference internal" href="#communicating-between-interpreters">Communicating Between Interpreters</a></li>
</ul>
</li>
<li><a class="reference internal" href="#basic-usage">Basic usage</a></li>
</ul>
</li>
</ul>
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<section id="module-concurrent.interpreters">
<span id="concurrent-interpreters-multiple-interpreters-in-the-same-process"></span><h1><code class="xref py py-mod docutils literal notranslate"><span class="pre">concurrent.interpreters</span></code> — Multiple interpreters in the same process<a class="headerlink" href="#module-concurrent.interpreters" title="Link to this heading">¶</a></h1>
<div class="versionadded">
<p><span class="versionmodified added">Added in version 3.14.</span></p>
</div>
<p><strong>Source code:</strong> <a class="extlink-source reference external" href="https://github.com/python/cpython/tree/3.14/Lib/concurrent/interpreters">Lib/concurrent/interpreters</a></p>
<hr class="docutils" />
<p>The <code class="xref py py-mod docutils literal notranslate"><span class="pre">concurrent.interpreters</span></code> module constructs higher-level
interfaces on top of the lower level <code class="xref py py-mod docutils literal notranslate"><span class="pre">_interpreters</span></code> module.</p>
<p>The module is primarily meant to provide a basic API for managing
interpreters (AKA “subinterpreters”) and running things in them.
Running mostly involves switching to an interpreter (in the current
thread) and calling a function in that execution context.</p>
<p>For concurrency, interpreters themselves (and this module) don’t
provide much more than isolation, which on its own isn’t useful.
Actual concurrency is available separately through
<a class="reference internal" href="threading.html#module-threading" title="threading: Thread-based parallelism."><code class="xref py py-mod docutils literal notranslate"><span class="pre">threads</span></code></a> See <a class="reference internal" href="#interp-concurrency">below</a></p>
<div class="admonition seealso">
<p class="admonition-title">See also</p>
<dl>
<dt><a class="reference internal" href="concurrent.futures.html#concurrent.futures.InterpreterPoolExecutor" title="concurrent.futures.InterpreterPoolExecutor"><code class="xref py py-class docutils literal notranslate"><span class="pre">InterpreterPoolExecutor</span></code></a></dt><dd><blockquote>
<div><p>combines threads with interpreters in a familiar interface.</p>
</div></blockquote>
</dd>
<dt><a class="reference internal" href="../howto/isolating-extensions.html#isolating-extensions-howto"><span class="std std-ref">Isolating Extension Modules</span></a></dt><dd><p>how to update an extension module to support multiple interpreters</p>
</dd>
</dl>
<p><span class="target" id="index-0"></span><a class="pep reference external" href="https://peps.python.org/pep-0554/"><strong>PEP 554</strong></a></p>
<p><span class="target" id="index-1"></span><a class="pep reference external" href="https://peps.python.org/pep-0734/"><strong>PEP 734</strong></a></p>
<p><span class="target" id="index-2"></span><a class="pep reference external" href="https://peps.python.org/pep-0684/"><strong>PEP 684</strong></a></p>
</div>
<div class="availability docutils container">
<p><a class="reference internal" href="intro.html#availability"><span class="std std-ref">Availability</span></a>: not WASI.</p>
<p>This module does not work or is not available on WebAssembly. See
<a class="reference internal" href="intro.html#wasm-availability"><span class="std std-ref">WebAssembly platforms</span></a> for more information.</p>
</div>
<section id="key-details">
<h2>Key details<a class="headerlink" href="#key-details" title="Link to this heading">¶</a></h2>
<p>Before we dive in further, there are a small number of details
to keep in mind about using multiple interpreters:</p>
<ul class="simple">
<li><p><a class="reference internal" href="#interp-isolation">isolated</a>, by default</p></li>
<li><p>no implicit threads</p></li>
<li><p>not all PyPI packages support use in multiple interpreters yet</p></li>
</ul>
</section>
<section id="introduction">
<span id="interpreters-intro"></span><h2>Introduction<a class="headerlink" href="#introduction" title="Link to this heading">¶</a></h2>
<p>An “interpreter” is effectively the execution context of the Python
runtime. It contains all of the state the runtime needs to execute
a program. This includes things like the import state and builtins.
(Each thread, even if there’s only the main thread, has some extra
runtime state, in addition to the current interpreter, related to
the current exception and the bytecode eval loop.)</p>
<p>The concept and functionality of the interpreter have been a part of
Python since version 2.2, but the feature was only available through
the C-API and not well known, and the <a class="reference internal" href="#interp-isolation">isolation</a>
was relatively incomplete until version 3.12.</p>
<section id="multiple-interpreters-and-isolation">
<span id="interp-isolation"></span><h3>Multiple Interpreters and Isolation<a class="headerlink" href="#multiple-interpreters-and-isolation" title="Link to this heading">¶</a></h3>
<p>A Python implementation may support using multiple interpreters in the
same process. CPython has this support. Each interpreter is
effectively isolated from the others (with a limited number of
carefully managed process-global exceptions to the rule).</p>
<p>That isolation is primarily useful as a strong separation between
distinct logical components of a program, where you want to have
careful control of how those components interact.</p>
<div class="admonition note">
<p class="admonition-title">Note</p>
<p>Interpreters in the same process can technically never be strictly
isolated from one another since there are few restrictions on memory
access within the same process. The Python runtime makes a best
effort at isolation but extension modules may easily violate that.
Therefore, do not use multiple interpreters in security-sensitive
situations, where they shouldn’t have access to each other’s data.</p>
</div>
</section>
<section id="running-in-an-interpreter">
<h3>Running in an Interpreter<a class="headerlink" href="#running-in-an-interpreter" title="Link to this heading">¶</a></h3>
<p>Running in a different interpreter involves switching to it in the
current thread and then calling some function. The runtime will
execute the function using the current interpreter’s state. The
<code class="xref py py-mod docutils literal notranslate"><span class="pre">concurrent.interpreters</span></code> module provides a basic API for
creating and managing interpreters, as well as the switch-and-call
operation.</p>
<p>No other threads are automatically started for the operation.
There is <a class="reference internal" href="#interp-call-in-thread">a helper</a> for that though.
There is another dedicated helper for calling the builtin
<a class="reference internal" href="functions.html#exec" title="exec"><code class="xref py py-func docutils literal notranslate"><span class="pre">exec()</span></code></a> in an interpreter.</p>
<p>When <a class="reference internal" href="functions.html#exec" title="exec"><code class="xref py py-func docutils literal notranslate"><span class="pre">exec()</span></code></a> (or <a class="reference internal" href="functions.html#eval" title="eval"><code class="xref py py-func docutils literal notranslate"><span class="pre">eval()</span></code></a>) are called in an interpreter,
they run using the interpreter’s <code class="xref py py-mod docutils literal notranslate"><span class="pre">__main__</span></code> module as the
“globals” namespace. The same is true for functions that aren’t
associated with any module. This is the same as how scripts invoked
from the command-line run in the <code class="xref py py-mod docutils literal notranslate"><span class="pre">__main__</span></code> module.</p>
</section>
<section id="concurrency-and-parallelism">
<span id="interp-concurrency"></span><h3>Concurrency and Parallelism<a class="headerlink" href="#concurrency-and-parallelism" title="Link to this heading">¶</a></h3>
<p>As noted earlier, interpreters do not provide any concurrency
on their own. They strictly represent the isolated execution
context the runtime will use <em>in the current thread</em>. That isolation
makes them similar to processes, but they still enjoy in-process
efficiency, like threads.</p>
<p>All that said, interpreters do naturally support certain flavors of
concurrency.
There’s a powerful side effect of that isolation. It enables a
different approach to concurrency than you can take with async or
threads. It’s a similar concurrency model to CSP or the actor model,
a model which is relatively easy to reason about.</p>
<p>You can take advantage of that concurrency model in a single thread,
switching back and forth between interpreters, Stackless-style.
However, this model is more useful when you combine interpreters
with multiple threads. This mostly involves starting a new thread,
where you switch to another interpreter and run what you want there.</p>
<p>Each actual thread in Python, even if you’re only running in the main
thread, has its own <em>current</em> execution context. Multiple threads can
use the same interpreter or different ones.</p>
<p>At a high level, you can think of the combination of threads and
interpreters as threads with opt-in sharing.</p>
<p>As a significant bonus, interpreters are sufficiently isolated that
they do not share the <a class="reference internal" href="../glossary.html#term-GIL"><span class="xref std std-term">GIL</span></a>, which means combining threads with
multiple interpreters enables full multi-core parallelism.
(This has been the case since Python 3.12.)</p>
</section>
<section id="communication-between-interpreters">
<h3>Communication Between Interpreters<a class="headerlink" href="#communication-between-interpreters" title="Link to this heading">¶</a></h3>
<p>In practice, multiple interpreters are useful only if we have a way
to communicate between them. This usually involves some form of
message passing, but can even mean sharing data in some carefully
managed way.</p>
<p>With this in mind, the <code class="xref py py-mod docutils literal notranslate"><span class="pre">concurrent.interpreters</span></code> module provides
a <a class="reference internal" href="queue.html#queue.Queue" title="queue.Queue"><code class="xref py py-class docutils literal notranslate"><span class="pre">queue.Queue</span></code></a> implementation, available through
<a class="reference internal" href="#concurrent.interpreters.create_queue" title="concurrent.interpreters.create_queue"><code class="xref py py-func docutils literal notranslate"><span class="pre">create_queue()</span></code></a>.</p>
</section>
<section id="sharing-objects">
<span id="interp-object-sharing"></span><h3>“Sharing” Objects<a class="headerlink" href="#sharing-objects" title="Link to this heading">¶</a></h3>
<p>Any data actually shared between interpreters loses the thread-safety
provided by the <a class="reference internal" href="../glossary.html#term-GIL"><span class="xref std std-term">GIL</span></a>. There are various options for dealing with
this in extension modules. However, from Python code the lack of
thread-safety means objects can’t actually be shared, with a few
exceptions. Instead, a copy must be created, which means mutable
objects won’t stay in sync.</p>
<p>By default, most objects are copied with <a class="reference internal" href="pickle.html#module-pickle" title="pickle: Convert Python objects to streams of bytes and back."><code class="xref py py-mod docutils literal notranslate"><span class="pre">pickle</span></code></a> when they are
passed to another interpreter. Nearly all of the immutable builtin
objects are either directly shared or copied efficiently. For example:</p>
<ul class="simple">
<li><p><a class="reference internal" href="constants.html#None" title="None"><code class="xref py py-const docutils literal notranslate"><span class="pre">None</span></code></a></p></li>
<li><p><a class="reference internal" href="functions.html#bool" title="bool"><code class="xref py py-class docutils literal notranslate"><span class="pre">bool</span></code></a> (<a class="reference internal" href="constants.html#True" title="True"><code class="xref py py-const docutils literal notranslate"><span class="pre">True</span></code></a> and <a class="reference internal" href="constants.html#False" title="False"><code class="xref py py-const docutils literal notranslate"><span class="pre">False</span></code></a>)</p></li>
<li><p><a class="reference internal" href="stdtypes.html#bytes" title="bytes"><code class="xref py py-class docutils literal notranslate"><span class="pre">bytes</span></code></a></p></li>
<li><p><a class="reference internal" href="stdtypes.html#str" title="str"><code class="xref py py-class docutils literal notranslate"><span class="pre">str</span></code></a></p></li>
<li><p><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></li>
<li><p><a class="reference internal" href="functions.html#float" title="float"><code class="xref py py-class docutils literal notranslate"><span class="pre">float</span></code></a></p></li>
<li><p><a class="reference internal" href="stdtypes.html#tuple" title="tuple"><code class="xref py py-class docutils literal notranslate"><span class="pre">tuple</span></code></a> (of similarly supported objects)</p></li>
</ul>
<p>There is a small number of Python types that actually share mutable
data between interpreters:</p>
<ul class="simple">
<li><p><a class="reference internal" href="stdtypes.html#memoryview" title="memoryview"><code class="xref py py-class docutils literal notranslate"><span class="pre">memoryview</span></code></a></p></li>
<li><p><a class="reference internal" href="#concurrent.interpreters.Queue" title="concurrent.interpreters.Queue"><code class="xref py py-class docutils literal notranslate"><span class="pre">Queue</span></code></a></p></li>
</ul>
</section>
</section>
<section id="reference">
<h2>Reference<a class="headerlink" href="#reference" title="Link to this heading">¶</a></h2>
<p>This module defines the following functions:</p>
<dl class="py function">
<dt class="sig sig-object py" id="concurrent.interpreters.list_all">
<span class="sig-prename descclassname"><span class="pre">concurrent.interpreters.</span></span><span class="sig-name descname"><span class="pre">list_all</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#concurrent.interpreters.list_all" title="Link to this definition">¶</a></dt>
<dd><p>Return a <a class="reference internal" href="stdtypes.html#list" title="list"><code class="xref py py-class docutils literal notranslate"><span class="pre">list</span></code></a> of <a class="reference internal" href="#concurrent.interpreters.Interpreter" title="concurrent.interpreters.Interpreter"><code class="xref py py-class docutils literal notranslate"><span class="pre">Interpreter</span></code></a> objects,
one for each existing interpreter.</p>
</dd></dl>
<dl class="py function">
<dt class="sig sig-object py" id="concurrent.interpreters.get_current">
<span class="sig-prename descclassname"><span class="pre">concurrent.interpreters.</span></span><span class="sig-name descname"><span class="pre">get_current</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#concurrent.interpreters.get_current" title="Link to this definition">¶</a></dt>
<dd><p>Return an <a class="reference internal" href="#concurrent.interpreters.Interpreter" title="concurrent.interpreters.Interpreter"><code class="xref py py-class docutils literal notranslate"><span class="pre">Interpreter</span></code></a> object for the currently running
interpreter.</p>
</dd></dl>
<dl class="py function">
<dt class="sig sig-object py" id="concurrent.interpreters.get_main">
<span class="sig-prename descclassname"><span class="pre">concurrent.interpreters.</span></span><span class="sig-name descname"><span class="pre">get_main</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#concurrent.interpreters.get_main" title="Link to this definition">¶</a></dt>
<dd><p>Return an <a class="reference internal" href="#concurrent.interpreters.Interpreter" title="concurrent.interpreters.Interpreter"><code class="xref py py-class docutils literal notranslate"><span class="pre">Interpreter</span></code></a> object for the main interpreter.
This is the interpreter the runtime created to run the <a class="reference internal" href="../glossary.html#term-REPL"><span class="xref std std-term">REPL</span></a>
or the script given at the command-line. It is usually the only one.</p>
</dd></dl>
<dl class="py function">
<dt class="sig sig-object py" id="concurrent.interpreters.create">
<span class="sig-prename descclassname"><span class="pre">concurrent.interpreters.</span></span><span class="sig-name descname"><span class="pre">create</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#concurrent.interpreters.create" title="Link to this definition">¶</a></dt>
<dd><p>Initialize a new (idle) Python interpreter
and return a <a class="reference internal" href="#concurrent.interpreters.Interpreter" title="concurrent.interpreters.Interpreter"><code class="xref py py-class docutils literal notranslate"><span class="pre">Interpreter</span></code></a> object for it.</p>
</dd></dl>
<dl class="py function">
<dt class="sig sig-object py" id="concurrent.interpreters.create_queue">
<span class="sig-prename descclassname"><span class="pre">concurrent.interpreters.</span></span><span class="sig-name descname"><span class="pre">create_queue</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#concurrent.interpreters.create_queue" title="Link to this definition">¶</a></dt>
<dd><p>Initialize a new cross-interpreter queue and return a <a class="reference internal" href="#concurrent.interpreters.Queue" title="concurrent.interpreters.Queue"><code class="xref py py-class docutils literal notranslate"><span class="pre">Queue</span></code></a>
object for it.</p>
</dd></dl>
<section id="interpreter-objects">
<h3>Interpreter objects<a class="headerlink" href="#interpreter-objects" title="Link to this heading">¶</a></h3>
<dl class="py class">
<dt class="sig sig-object py" id="concurrent.interpreters.Interpreter">
<em class="property"><span class="k"><span class="pre">class</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">concurrent.interpreters.</span></span><span class="sig-name descname"><span class="pre">Interpreter</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">id</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#concurrent.interpreters.Interpreter" title="Link to this definition">¶</a></dt>
<dd><p>A single interpreter in the current process.</p>
<p>Generally, <a class="reference internal" href="#concurrent.interpreters.Interpreter" title="concurrent.interpreters.Interpreter"><code class="xref py py-class docutils literal notranslate"><span class="pre">Interpreter</span></code></a> shouldn’t be called directly.
Instead, use <a class="reference internal" href="#concurrent.interpreters.create" title="concurrent.interpreters.create"><code class="xref py py-func docutils literal notranslate"><span class="pre">create()</span></code></a> or one of the other module functions.</p>
<dl class="py attribute">
<dt class="sig sig-object py" id="concurrent.interpreters.Interpreter.id">
<span class="sig-name descname"><span class="pre">id</span></span><a class="headerlink" href="#concurrent.interpreters.Interpreter.id" title="Link to this definition">¶</a></dt>
<dd><p>(read-only)</p>
<p>The underlying interpreter’s ID.</p>
</dd></dl>
<dl class="py attribute">
<dt class="sig sig-object py" id="concurrent.interpreters.Interpreter.whence">
<span class="sig-name descname"><span class="pre">whence</span></span><a class="headerlink" href="#concurrent.interpreters.Interpreter.whence" title="Link to this definition">¶</a></dt>
<dd><p>(read-only)</p>
<p>A string describing where the interpreter came from.</p>
</dd></dl>
<dl class="py method">
<dt class="sig sig-object py" id="concurrent.interpreters.Interpreter.is_running">
<span class="sig-name descname"><span class="pre">is_running</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#concurrent.interpreters.Interpreter.is_running" title="Link to this definition">¶</a></dt>
<dd><p>Return <code class="docutils literal notranslate"><span class="pre">True</span></code> if the interpreter is currently executing code
in its <code class="xref py py-mod docutils literal notranslate"><span class="pre">__main__</span></code> module and <code class="docutils literal notranslate"><span class="pre">False</span></code> otherwise.</p>
</dd></dl>
<dl class="py method">
<dt class="sig sig-object py" id="concurrent.interpreters.Interpreter.close">
<span class="sig-name descname"><span class="pre">close</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#concurrent.interpreters.Interpreter.close" title="Link to this definition">¶</a></dt>
<dd><p>Finalize and destroy the interpreter.</p>
</dd></dl>
<dl class="py method">
<dt class="sig sig-object py" id="concurrent.interpreters.Interpreter.prepare_main">
<span class="sig-name descname"><span class="pre">prepare_main</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">ns</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em>, <em class="sig-param"><span class="o"><span class="pre">**</span></span><span class="n"><span class="pre">kwargs</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#concurrent.interpreters.Interpreter.prepare_main" title="Link to this definition">¶</a></dt>
<dd><p>Bind objects in the interpreter’s <code class="xref py py-mod docutils literal notranslate"><span class="pre">__main__</span></code> module.</p>
<p>Some objects are actually shared and some are copied efficiently,
but most are copied via <a class="reference internal" href="pickle.html#module-pickle" title="pickle: Convert Python objects to streams of bytes and back."><code class="xref py py-mod docutils literal notranslate"><span class="pre">pickle</span></code></a>. See <a class="reference internal" href="#interp-object-sharing"><span class="std std-ref">“Sharing” Objects</span></a>.</p>
</dd></dl>
<dl class="py method">
<dt class="sig sig-object py" id="concurrent.interpreters.Interpreter.exec">
<span class="sig-name descname"><span class="pre">exec</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">code</span></span></em>, <em class="sig-param"><span class="positional-only-separator o"><abbr title="Positional-only parameter separator (PEP 570)"><span class="pre">/</span></abbr></span></em>, <em class="sig-param"><span class="n"><span class="pre">dedent</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">True</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#concurrent.interpreters.Interpreter.exec" title="Link to this definition">¶</a></dt>
<dd><p>Run the given source code in the interpreter (in the current thread).</p>
</dd></dl>
<dl class="py method">
<dt class="sig sig-object py" id="concurrent.interpreters.Interpreter.call">
<span class="sig-name descname"><span class="pre">call</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">callable</span></span></em>, <em class="sig-param"><span class="positional-only-separator o"><abbr title="Positional-only parameter separator (PEP 570)"><span class="pre">/</span></abbr></span></em>, <em class="sig-param"><span class="o"><span class="pre">*</span></span><span class="n"><span class="pre">args</span></span></em>, <em class="sig-param"><span class="o"><span class="pre">**</span></span><span class="n"><span class="pre">kwargs</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#concurrent.interpreters.Interpreter.call" title="Link to this definition">¶</a></dt>
<dd><p>Return the result of calling running the given function in the
interpreter (in the current thread).</p>
</dd></dl>
<dl class="py method" id="interp-call-in-thread">
<dt class="sig sig-object py" id="concurrent.interpreters.Interpreter.call_in_thread">
<span class="sig-name descname"><span class="pre">call_in_thread</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">callable</span></span></em>, <em class="sig-param"><span class="positional-only-separator o"><abbr title="Positional-only parameter separator (PEP 570)"><span class="pre">/</span></abbr></span></em>, <em class="sig-param"><span class="o"><span class="pre">*</span></span><span class="n"><span class="pre">args</span></span></em>, <em class="sig-param"><span class="o"><span class="pre">**</span></span><span class="n"><span class="pre">kwargs</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#concurrent.interpreters.Interpreter.call_in_thread" title="Link to this definition">¶</a></dt>
<dd><p>Run the given function in the interpreter (in a new thread).</p>
</dd></dl>
</dd></dl>
</section>
<section id="exceptions">
<h3>Exceptions<a class="headerlink" href="#exceptions" title="Link to this heading">¶</a></h3>
<dl class="py exception">
<dt class="sig sig-object py" id="concurrent.interpreters.InterpreterError">
<em class="property"><span class="k"><span class="pre">exception</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">concurrent.interpreters.</span></span><span class="sig-name descname"><span class="pre">InterpreterError</span></span><a class="headerlink" href="#concurrent.interpreters.InterpreterError" title="Link to this definition">¶</a></dt>
<dd><p>This exception, a subclass of <a class="reference internal" href="exceptions.html#Exception" title="Exception"><code class="xref py py-exc docutils literal notranslate"><span class="pre">Exception</span></code></a>, is raised when
an interpreter-related error happens.</p>
</dd></dl>
<dl class="py exception">
<dt class="sig sig-object py" id="concurrent.interpreters.InterpreterNotFoundError">
<em class="property"><span class="k"><span class="pre">exception</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">concurrent.interpreters.</span></span><span class="sig-name descname"><span class="pre">InterpreterNotFoundError</span></span><a class="headerlink" href="#concurrent.interpreters.InterpreterNotFoundError" title="Link to this definition">¶</a></dt>
<dd><p>This exception, a subclass of <a class="reference internal" href="#concurrent.interpreters.InterpreterError" title="concurrent.interpreters.InterpreterError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">InterpreterError</span></code></a>, is raised when
the targeted interpreter no longer exists.</p>
</dd></dl>
<dl class="py exception">
<dt class="sig sig-object py" id="concurrent.interpreters.ExecutionFailed">
<em class="property"><span class="k"><span class="pre">exception</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">concurrent.interpreters.</span></span><span class="sig-name descname"><span class="pre">ExecutionFailed</span></span><a class="headerlink" href="#concurrent.interpreters.ExecutionFailed" title="Link to this definition">¶</a></dt>
<dd><p>This exception, a subclass of <a class="reference internal" href="#concurrent.interpreters.InterpreterError" title="concurrent.interpreters.InterpreterError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">InterpreterError</span></code></a>, is raised when
the running code raised an uncaught exception.</p>
<dl class="py attribute">
<dt class="sig sig-object py" id="concurrent.interpreters.ExecutionFailed.excinfo">
<span class="sig-name descname"><span class="pre">excinfo</span></span><a class="headerlink" href="#concurrent.interpreters.ExecutionFailed.excinfo" title="Link to this definition">¶</a></dt>
<dd><p>A basic snapshot of the exception raised in the other interpreter.</p>
</dd></dl>
</dd></dl>
<dl class="py exception">
<dt class="sig sig-object py" id="concurrent.interpreters.NotShareableError">
<em class="property"><span class="k"><span class="pre">exception</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">concurrent.interpreters.</span></span><span class="sig-name descname"><span class="pre">NotShareableError</span></span><a class="headerlink" href="#concurrent.interpreters.NotShareableError" title="Link to this definition">¶</a></dt>
<dd><p>This exception, a subclass of <a class="reference internal" href="exceptions.html#TypeError" title="TypeError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">TypeError</span></code></a>, is raised when
an object cannot be sent to another interpreter.</p>
</dd></dl>
</section>
<section id="communicating-between-interpreters">
<h3>Communicating Between Interpreters<a class="headerlink" href="#communicating-between-interpreters" title="Link to this heading">¶</a></h3>
<dl class="py class">
<dt class="sig sig-object py" id="concurrent.interpreters.Queue">
<em class="property"><span class="k"><span class="pre">class</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">concurrent.interpreters.</span></span><span class="sig-name descname"><span class="pre">Queue</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">id</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#concurrent.interpreters.Queue" title="Link to this definition">¶</a></dt>
<dd><p>A wrapper around a low-level, cross-interpreter queue, which
implements the <a class="reference internal" href="queue.html#queue.Queue" title="queue.Queue"><code class="xref py py-class docutils literal notranslate"><span class="pre">queue.Queue</span></code></a> interface. The underlying queue
can only be created through <a class="reference internal" href="#concurrent.interpreters.create_queue" title="concurrent.interpreters.create_queue"><code class="xref py py-func docutils literal notranslate"><span class="pre">create_queue()</span></code></a>.</p>
<p>Some objects are actually shared and some are copied efficiently,
but most are copied via <a class="reference internal" href="pickle.html#module-pickle" title="pickle: Convert Python objects to streams of bytes and back."><code class="xref py py-mod docutils literal notranslate"><span class="pre">pickle</span></code></a>. See <a class="reference internal" href="#interp-object-sharing"><span class="std std-ref">“Sharing” Objects</span></a>.</p>
<dl class="py attribute">
<dt class="sig sig-object py" id="concurrent.interpreters.Queue.id">
<span class="sig-name descname"><span class="pre">id</span></span><a class="headerlink" href="#concurrent.interpreters.Queue.id" title="Link to this definition">¶</a></dt>
<dd><p>(read-only)</p>
<p>The queue’s ID.</p>
</dd></dl>
</dd></dl>
<dl class="py exception">
<dt class="sig sig-object py" id="concurrent.interpreters.QueueEmptyError">
<em class="property"><span class="k"><span class="pre">exception</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">concurrent.interpreters.</span></span><span class="sig-name descname"><span class="pre">QueueEmptyError</span></span><a class="headerlink" href="#concurrent.interpreters.QueueEmptyError" title="Link to this definition">¶</a></dt>
<dd><p>This exception, a subclass of <a class="reference internal" href="queue.html#queue.Empty" title="queue.Empty"><code class="xref py py-exc docutils literal notranslate"><span class="pre">queue.Empty</span></code></a>, is raised from
<code class="xref py py-meth docutils literal notranslate"><span class="pre">Queue.get()</span></code> and <code class="xref py py-meth docutils literal notranslate"><span class="pre">Queue.get_nowait()</span></code> when the queue
is empty.</p>
</dd></dl>
<dl class="py exception">
<dt class="sig sig-object py" id="concurrent.interpreters.QueueFullError">
<em class="property"><span class="k"><span class="pre">exception</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">concurrent.interpreters.</span></span><span class="sig-name descname"><span class="pre">QueueFullError</span></span><a class="headerlink" href="#concurrent.interpreters.QueueFullError" title="Link to this definition">¶</a></dt>
<dd><p>This exception, a subclass of <a class="reference internal" href="queue.html#queue.Full" title="queue.Full"><code class="xref py py-exc docutils literal notranslate"><span class="pre">queue.Full</span></code></a>, is raised from
<code class="xref py py-meth docutils literal notranslate"><span class="pre">Queue.put()</span></code> and <code class="xref py py-meth docutils literal notranslate"><span class="pre">Queue.put_nowait()</span></code> when the queue
is full.</p>
</dd></dl>
</section>
</section>
<section id="basic-usage">
<h2>Basic usage<a class="headerlink" href="#basic-usage" title="Link to this heading">¶</a></h2>
<p>Creating an interpreter and running code in it:</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="kn">from</span><span class="w"> </span><span class="nn">concurrent</span><span class="w"> </span><span class="kn">import</span> <span class="n">interpreters</span>
<span class="n">interp</span> <span class="o">=</span> <span class="n">interpreters</span><span class="o">.</span><span class="n">create</span><span class="p">()</span>
<span class="c1"># Run in the current OS thread.</span>
<span class="n">interp</span><span class="o">.</span><span class="n">exec</span><span class="p">(</span><span class="s1">'print("spam!")'</span><span class="p">)</span>
<span class="n">interp</span><span class="o">.</span><span class="n">exec</span><span class="p">(</span><span class="s2">"""if True:</span>
<span class="s2"> print('spam!')</span>
<span class="s2"> """</span><span class="p">)</span>
<span class="kn">from</span><span class="w"> </span><span class="nn">textwrap</span><span class="w"> </span><span class="kn">import</span> <span class="n">dedent</span>
<span class="n">interp</span><span class="o">.</span><span class="n">exec</span><span class="p">(</span><span class="n">dedent</span><span class="p">(</span><span class="s2">"""</span>
<span class="s2"> print('spam!')</span>
<span class="s2"> """</span><span class="p">))</span>
<span class="k">def</span><span class="w"> </span><span class="nf">run</span><span class="p">(</span><span class="n">arg</span><span class="p">):</span>
<span class="k">return</span> <span class="n">arg</span>
<span class="n">res</span> <span class="o">=</span> <span class="n">interp</span><span class="o">.</span><span class="n">call</span><span class="p">(</span><span class="n">run</span><span class="p">,</span> <span class="s1">'spam!'</span><span class="p">)</span>
<span class="nb">print</span><span class="p">(</span><span class="n">res</span><span class="p">)</span>
<span class="k">def</span><span class="w"> </span><span class="nf">run</span><span class="p">():</span>
<span class="nb">print</span><span class="p">(</span><span class="s1">'spam!'</span><span class="p">)</span>
<span class="n">interp</span><span class="o">.</span><span class="n">call</span><span class="p">(</span><span class="n">run</span><span class="p">)</span>
<span class="c1"># Run in new OS thread.</span>
<span class="n">t</span> <span class="o">=</span> <span class="n">interp</span><span class="o">.</span><span class="n">call_in_thread</span><span class="p">(</span><span class="n">run</span><span class="p">)</span>
<span class="n">t</span><span class="o">.</span><span class="n">join</span><span class="p">()</span>
</pre></div>
</div>
</section>
</section>
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<h3><a href="../contents.html">Table of Contents</a></h3>
<ul>
<li><a class="reference internal" href="#"><code class="xref py py-mod docutils literal notranslate"><span class="pre">concurrent.interpreters</span></code> — Multiple interpreters in the same process</a><ul>
<li><a class="reference internal" href="#key-details">Key details</a></li>
<li><a class="reference internal" href="#introduction">Introduction</a><ul>
<li><a class="reference internal" href="#multiple-interpreters-and-isolation">Multiple Interpreters and Isolation</a></li>
<li><a class="reference internal" href="#running-in-an-interpreter">Running in an Interpreter</a></li>
<li><a class="reference internal" href="#concurrency-and-parallelism">Concurrency and Parallelism</a></li>
<li><a class="reference internal" href="#communication-between-interpreters">Communication Between Interpreters</a></li>
<li><a class="reference internal" href="#sharing-objects">“Sharing” Objects</a></li>
</ul>
</li>
<li><a class="reference internal" href="#reference">Reference</a><ul>
<li><a class="reference internal" href="#interpreter-objects">Interpreter objects</a></li>
<li><a class="reference internal" href="#exceptions">Exceptions</a></li>
<li><a class="reference internal" href="#communicating-between-interpreters">Communicating Between Interpreters</a></li>
</ul>
</li>
<li><a class="reference internal" href="#basic-usage">Basic usage</a></li>
</ul>
</li>
</ul>
</div>
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Last updated on Oct 07, 2025 (10:02 UTC).
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