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GeezerVison is showing github.com — gh-144446: Fix some frame object thread-safety issues by colesbury · Pull Request #144479 · python/cpython

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@colesbury

@colesbury colesbury commented Feb 4, 2026 •
edited by bedevere-app Bot
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Fix thread-safety issues when accessing frame attributes while another thread is executing the frame:

  • Add critical section to frame_repr() to prevent races when accessing the frame's code object and line number

  • Add _Py_NO_SANITIZE_THREAD to PyUnstable_InterpreterFrame_GetLasti() to allow intentional racy reads of instr_ptr.

  • Fix take_ownership() to not write to the original frame's f_executable

  • Issue: Data races with frame objects #144446

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@colesbury
pythongh-144446: Fix some frame object thread-safety issues
25f9328 
Fix thread-safety issues when accessing frame attributes while another
thread is executing the frame:

- Add critical section to frame_repr() to prevent races when accessing
  the frame's code object and line number

- Add _Py_NO_SANITIZE_THREAD to PyUnstable_InterpreterFrame_GetLasti()
  to allow intentional racy reads of instr_ptr.

- Fix take_ownership() to not write to the original frame's f_executable
@bedevere-app bedevere-app Bot mentioned this pull request Feb 4, 2026
Data races with frame objects #144446
Open
2 of 3 tasks
@colesbury colesbury added the topic-free-threading label Feb 4, 2026
@colesbury
Fix blurb
ce6f092
@colesbury

colesbury commented Feb 4, 2026

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There are still some races when accessing variables through frame.f_locals, which will be address separately.
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@colesbury
colesbury marked this pull request as ready for review February 4, 2026 18:08
@colesbury
colesbury requested a review from markshannon as a code owner February 4, 2026 18:08
@bedevere-app bedevere-app Bot added the awaiting core review label Feb 4, 2026
@colesbury
colesbury requested a review from mpage February 4, 2026 18:37
@colesbury colesbury added the needs backport to 3.14 bugs and security fixes label Feb 4, 2026
kumaraditya303
kumaraditya303 reviewed Feb 5, 2026
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Comment thread Lib/test/test_free_threading/test_frame.py Resolved

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sergey-miryanov
sergey-miryanov reviewed Feb 5, 2026
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Comment thread Python/frame.c Resolved

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@colesbury
Change test docstrings to comments
c6e8294
mpage
mpage approved these changes Feb 6, 2026
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LGTM

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@bedevere-app bedevere-app Bot added awaiting merge and removed awaiting core review labels Feb 6, 2026
kumaraditya303
kumaraditya303 approved these changes Feb 6, 2026
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@colesbury
colesbury merged commit 5bb3bbb into python:main Feb 6, 2026
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@colesbury
colesbury deleted the gh-144446-frame-free-threading branch February 6, 2026 14:43
@bedevere-app bedevere-app Bot removed the awaiting merge label Feb 6, 2026
@miss-islington-app

miss-islington-app Bot commented Feb 6, 2026

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Thanks @colesbury for the PR 🌮🎉.. I'm working now to backport this PR to: 3.14.
🐍🍒⛏🤖
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miss-islington pushed a commit to miss-islington/cpython that referenced this pull request Feb 6, 2026
@colesbury @miss-islington
pythongh-144446: Fix some frame object thread-safety issues (pythongh…
d92a7fb 
…-144479)

Fix thread-safety issues when accessing frame attributes while another
thread is executing the frame:

- Add critical section to frame_repr() to prevent races when accessing
  the frame's code object and line number

- Add _Py_NO_SANITIZE_THREAD to PyUnstable_InterpreterFrame_GetLasti()
  to allow intentional racy reads of instr_ptr.

- Fix take_ownership() to not write to the original frame's f_executable
(cherry picked from commit 5bb3bbb)

Co-authored-by: Sam Gross <[email protected]>
@bedevere-app

bedevere-app Bot commented Feb 6, 2026

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GH-144546 is a backport of this pull request to the 3.14 branch.
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@bedevere-app bedevere-app Bot removed the needs backport to 3.14 bugs and security fixes label Feb 6, 2026
colesbury added a commit that referenced this pull request Feb 6, 2026
@miss-islington @colesbury
[3.14] gh-144446: Fix some frame object thread-safety issues (gh-144479…
6006005 
…) (#144546)

Fix thread-safety issues when accessing frame attributes while another
thread is executing the frame:

- Add critical section to frame_repr() to prevent races when accessing
  the frame's code object and line number

- Add _Py_NO_SANITIZE_THREAD to PyUnstable_InterpreterFrame_GetLasti()
  to allow intentional racy reads of instr_ptr.

- Fix take_ownership() to not write to the original frame's f_executable
(cherry picked from commit 5bb3bbb)

Co-authored-by: Sam Gross <[email protected]>
thunder-coding pushed a commit to thunder-coding/cpython that referenced this pull request Feb 15, 2026
@colesbury @thunder-coding
pythongh-144446: Fix some frame object thread-safety issues (pythongh…
5f30178 
…-144479)

Fix thread-safety issues when accessing frame attributes while another
thread is executing the frame:

- Add critical section to frame_repr() to prevent races when accessing
  the frame's code object and line number

- Add _Py_NO_SANITIZE_THREAD to PyUnstable_InterpreterFrame_GetLasti()
  to allow intentional racy reads of instr_ptr.

- Fix take_ownership() to not write to the original frame's f_executable
ljfp pushed a commit to ljfp/cpython that referenced this pull request Apr 25, 2026
@colesbury @ljfp
pythongh-144446: Fix some frame object thread-safety issues (pythongh…
773fb83 
…-144479)

Fix thread-safety issues when accessing frame attributes while another
thread is executing the frame:

- Add critical section to frame_repr() to prevent races when accessing
  the frame's code object and line number

- Add _Py_NO_SANITIZE_THREAD to PyUnstable_InterpreterFrame_GetLasti()
  to allow intentional racy reads of instr_ptr.

- Fix take_ownership() to not write to the original frame's f_executable
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Reviewers

@sergey-miryanov sergey-miryanov sergey-miryanov left review comments
@mpage mpage mpage approved these changes
@kumaraditya303 kumaraditya303 kumaraditya303 approved these changes
@markshannon markshannon Awaiting requested review from markshannon markshannon is a code owner

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4 participants

@colesbury @sergey-miryanov @mpage @kumaraditya303
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