gh-119344: Make critical section API public by colesbury · Pull Request #119353 · python/cpython · GitHub

This makes the following macros public as part of the non-limited C-API for locking a single object or two objects at once.

Py_BEGIN_CRITICAL_SECTION(op) / Py_END_CRITICAL_SECTION()
Py_BEGIN_CRITICAL_SECTION2(a, b) / Py_END_CRITICAL_SECTION2()

The following supporting functions and types are also public for use by bindings from other languages:

PyAPI_FUNC(void) PyCriticalSection_Begin(PyCriticalSection *c, PyObject *op)
PyAPI_FUNC(void) PyCriticalSection_End(PyCriticalSection *c)
PyAPI_FUNC(void) PyCriticalSection_Begin2(PyCriticalSection2 *c, PyObject *a, PyObject *b)
PyAPI_FUNC(void) PyCriticalSection_End2(PyCriticalSection2 *c)
PyCriticalSection (struct contents private)
PyCriticalSection2 (struct contents private)

Note that the more esoteric APIs are still internal-only as part of pycore_critical_section.h.

Issue: Make Py_BEGIN_CRITICAL_SECTION() and Py_END_CRITICAL_SECTION() public in the non-limited C API #119344

See also C-API WG Issue:

Make critical section API public as part of non-limited C API capi-workgroup/decisions#26 (comment)

Docs:

https://cpython-previews--119353.org.readthedocs.build/en/119353/c-api/init.html#python-critical-section-api

Did this API got an exception to be added to Python 3.13?

Would it be possible to add "cs_" in the name? It helps refactoring and to navigate in the code.

_prev => _cs_prev
_mutex => _cs_mutex

Same suggestion for PyCriticalSection2.

I've renamed the fields

Maybe move this doc to Doc/c-api/init.rst, or merge it with Doc/c-api/init.rst?

I think the file documentation is still useful even with the public Doc/c-api/init.rst docs. The file docs talk more about specific internals like PyThreadState.critical_section.

Looks good, thank you! I have a few suggestions for the docs:

Mabye add a label for easy referencing in the future.

I've added a label

Co-authored-by: Petr Viktorin <encukou@gmail.com> Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com> Co-authored-by: Victor Stinner <vstinner@python.org>

@Yhg1s - this PR makes the critical section API public. Is it acceptable to include this in 3.13?

There's a bunch of refactoring to make the API public, but no new functionality.

Yes, this can go into 3.13 if it gets into beta 3. (How many more APIs do you think we'll need for 3.13? :P)

This is the last one, I promise!

LGTM, thanks for the update.

Thanks @colesbury for the PR 🌮🎉.. I'm working now to backport this PR to: 3.13.
🐍🍒⛏🤖

Sorry, @colesbury, I could not cleanly backport this to 3.13 due to a conflict.
Please backport using cherry_picker on command line.

cherry_picker 8f17d69b7bc906e8407095317842cc0fd52cd84a 3.13

…9353) This makes the following macros public as part of the non-limited C-API for locking a single object or two objects at once. * `Py_BEGIN_CRITICAL_SECTION(op)` / `Py_END_CRITICAL_SECTION()` * `Py_BEGIN_CRITICAL_SECTION2(a, b)` / `Py_END_CRITICAL_SECTION2()` The supporting functions and structs used by the macros are also exposed for cases where C macros are not available. (cherry picked from commit 8f17d69) Co-authored-by: Sam Gross <colesbury@gmail.com>

GH-120856 is a backport of this pull request to the 3.13 branch.

This makes the following macros public as part of the non-limited C-API for locking a single object or two objects at once. * `Py_BEGIN_CRITICAL_SECTION(op)` / `Py_END_CRITICAL_SECTION()` * `Py_BEGIN_CRITICAL_SECTION2(a, b)` / `Py_END_CRITICAL_SECTION2()` The supporting functions and structs used by the macros are also exposed for cases where C macros are not available. (cherry picked from commit 8f17d69)

This makes the following macros public as part of the non-limited C-API for locking a single object or two objects at once. * `Py_BEGIN_CRITICAL_SECTION(op)` / `Py_END_CRITICAL_SECTION()` * `Py_BEGIN_CRITICAL_SECTION2(a, b)` / `Py_END_CRITICAL_SECTION2()` The supporting functions and structs used by the macros are also exposed for cases where C macros are not available.

pythongh-119344 : Make critical section API public

861f3a6

bedevere-app Bot mentioned this pull request May 21, 2024

Make Py_BEGIN_CRITICAL_SECTION() and Py_END_CRITICAL_SECTION() public in the non-limited C API #119344

Closed

colesbury added the topic-free-threading label May 21, 2024

colesbury mentioned this pull request May 21, 2024

Make critical section API public as part of non-limited C API capi-workgroup/decisions#26

Closed

colesbury added 6 commits May 31, 2024 15:41

Add missing functions and public C API test

0bc4a93

Merge branch 'main' into pythongh-119344 -critical-section-api

ee014a6

Remove leading underscore before _PyCriticalSection

75c96fe

Clean up function definitions

3941794

Fix C syntax error

0e7873b

Add documentation

4c7df8d

colesbury marked this pull request as ready for review June 20, 2024 23:10

colesbury requested review from a team, erlend-aasland, markshannon and methane as code owners June 20, 2024 23:10

bedevere-app Bot added the awaiting core review label Jun 20, 2024

colesbury added the topic-C-API label Jun 20, 2024

Fix syntax error

c61ba72

colesbury added the needs backport to 3.13 bugs and security fixes label Jun 20, 2024

colesbury requested review from ezio-melotti and hugovk as code owners June 20, 2024 23:46

colesbury force-pushed the gh-119344-critical-section-api branch from fb1579a to c61ba72 Compare June 20, 2024 23:53

colesbury requested review from encukou and vstinner and removed request for ezio-melotti and hugovk June 20, 2024 23:53

vstinner reviewed Jun 21, 2024

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encukou reviewed Jun 21, 2024

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Comment thread Doc/c-api/init.rst Outdated

Comment thread Doc/c-api/init.rst Outdated

Comment thread Doc/c-api/init.rst

picnixz reviewed Jun 21, 2024

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Apply suggestions from code review

89405ca

Co-authored-by: Petr Viktorin <encukou@gmail.com> Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com> Co-authored-by: Victor Stinner <vstinner@python.org>

colesbury added 3 commits June 21, 2024 10:53

Sizes and contents

dc50fff

Rename PyCriticalSection fields

c3073b0

Add section label

493d062

vstinner approved these changes Jun 21, 2024

View reviewed changes

bedevere-app Bot added awaiting merge and removed awaiting core review labels Jun 21, 2024

colesbury merged commit 8f17d69 into python:main Jun 21, 2024

bedevere-app Bot removed the awaiting merge label Jun 21, 2024

colesbury deleted the gh-119344-critical-section-api branch June 21, 2024 19:50

miss-islington-app Bot assigned colesbury Jun 21, 2024

bedevere-app Bot removed the needs backport to 3.13 bugs and security fixes label Jun 21, 2024

colesbury removed their assignment Jul 19, 2024

ngoldbaum mentioned this pull request Jun 10, 2025

Expose critical section APIs that accept a PyMutex rather than an object capi-workgroup/decisions#67

Closed

coderabbitai Bot mentioned this pull request Aug 20, 2026

cpyext: what a Cython module reaches for, and the descriptor-cache order it made visible youknowone/pyre#1363

Merged

+              // Python releases without a deprecation period.
+              struct PyCriticalSection {
+                  // Tagged pointer to an outer active critical section (or 0).
+                  uintptr_t _prev;

+              #  error "this header file must not be included directly"
+              #endif
+              // Python critical sections


		.. versionadded:: 3.13

		Python Critical Section API

gh-119344: Make critical section API public by colesbury · Pull Request #119353 · python/cpython · GitHub

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gh-119344: Make critical section API public - #119353

gh-119344: Make critical section API public#119353colesbury merged 12 commits intopython:mainpython/cpython:mainfrom colesbury:gh-119344-critical-section-apicolesbury/cpython:gh-119344-critical-section-apiCopy head branch name to clipboard

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gh-119344: Make critical section API public#119353
colesbury merged 12 commits into
python:mainfrom
colesbury:gh-119344-critical-section-api

colesbury commented May 21, 2024 •
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