Files
cpython/Include
Gregory P. Smith 9face218e7 [3.13] gh-87135: Hang non-main threads that attempt to acquire the GIL during finalization (GH-105805) (GH-137827)
* [3.13] gh-87135: Hang non-main threads that attempt to acquire the GIL during finalization (GH-105805)

Instead of surprise crashes and memory corruption, we now hang threads that attempt to re-enter the Python interpreter after Python runtime finalization has started. These are typically daemon threads (our long standing mis-feature) but could also be threads spawned by extension modules that then try to call into Python. This marks the `PyThread_exit_thread` public C API as deprecated as there is no plausible safe way to accomplish that on any supported platform in the face of things like C++ code with finalizers anywhere on a thread's stack. Doing this was the least bad option.

(cherry picked from commit 8cc5aa47ee)

Co-authored-by: Jeremy Maitin-Shepard <jeremy@jeremyms.com>
Co-authored-by: Gregory P. Smith <greg@krypto.org>

* state "3.13.7 and earlier"
* backport: do not add the deprecated marker
* fix Py_IsFinalizing doc ref

---------

Co-authored-by: Jeremy Maitin-Shepard <jeremy@jeremyms.com>
2025-08-17 09:08:14 -07:00
..
2025-08-14 20:13:25 +02:00

The Python C API
================

The C API is divided into these sections:

1. ``Include/``: Limited API
2. ``Include/cpython/``: CPython implementation details
3. ``Include/cpython/``, names with the ``PyUnstable_`` prefix: API that can
   change between minor releases
4. ``Include/internal/``, and any name with ``_`` prefix: The internal API

Information on changing the C API is available `in the developer guide`_

.. _in the developer guide: https://devguide.python.org/c-api/