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GH-100964: Fix reference cycle in exhausted generator frames#141112

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savannahostrowski merged 6 commits intopython:mainfrom
savannahostrowski:reference-cycle
Dec 17, 2025
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GH-100964: Fix reference cycle in exhausted generator frames#141112
savannahostrowski merged 6 commits intopython:mainfrom
savannahostrowski:reference-cycle

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@savannahostrowski savannahostrowski commented Nov 6, 2025 •
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So after spelunking here it appears that the issue here is that we can't clear frame->previous after _PyFrame_ClearExceptCode in clear_gen_frame because _PyFrame_ClearExceptCode calls take_ownership which copies the frame with a stale previous pointer. This makes f_back point to the caller, instead of None.

@savannahostrowski savannahostrowski added needs backport to 3.13 bugs and security fixes needs backport to 3.14 bugs and security fixes labels Nov 6, 2025
@bedevere-app bedevere-app bot mentioned this pull request Nov 6, 2025
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savannahostrowski commented Dec 1, 2025

@markshannon Are you still the right person to take a look at this 😄 ?

@savannahostrowski savannahostrowski deleted the reference-cycle branch December 4, 2025 22:59
@savannahostrowski savannahostrowski restored the reference-cycle branch December 4, 2025 22:59
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kumaraditya303 commented Dec 17, 2025

I came across this bug today while writing an asyncio test and this fixed it.

ping @markshannon for review

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Nice fix

@savannahostrowski savannahostrowski enabled auto-merge (squash) December 17, 2025 18:52
@savannahostrowski savannahostrowski merged commit 92243dc into python:main Dec 17, 2025
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miss-islington-app bot commented Dec 17, 2025

Thanks @savannahostrowski for the PR 🌮🎉.. I'm working now to backport this PR to: 3.13, 3.14.
🐍🍒⛏🤖

miss-islington pushed a commit to miss-islington/cpython that referenced this pull request Dec 17, 2025
@savannahostrowski @miss-islington
pythonGH-100964: Fix reference cycle in exhausted generator frames (p…
acc0640 
…ythonGH-141112)

(cherry picked from commit 92243dc)

Co-authored-by: Savannah Ostrowski <savannah@python.org>
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miss-islington-app bot commented Dec 17, 2025

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

cherry_picker 92243dc62ce10715ab0d9074b23dea5a1bfa9dcc 3.13

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bedevere-app bot commented Dec 17, 2025

GH-142902 is a backport of this pull request to the 3.14 branch.

@bedevere-app bedevere-app bot removed the needs backport to 3.14 bugs and security fixes label Dec 17, 2025
savannahostrowski added a commit that referenced this pull request Dec 17, 2025
@miss-islington @savannahostrowski
[3.14] GH-100964: Fix reference cycle in exhausted generator frames (G…
7134b40 
…H-141112) (#142902)

GH-100964: Fix reference cycle in exhausted generator frames (GH-141112)
(cherry picked from commit 92243dc)

Co-authored-by: Savannah Ostrowski <savannah@python.org>
savannahostrowski added a commit that referenced this pull request Dec 17, 2025
@savannahostrowski
[3.13] GH-100964: Fix reference cycle in exhausted generator frames (…
8f7c4f1 
…G… (#142904)

* [3.13] GH-100964: Fix reference cycle in exhausted generator frames (GH-141112)
(cherry picked from commit 92243dc)

Co-authored-by: Savannah Ostrowski <savannah@python.org>
@kumaraditya303 kumaraditya303 removed the needs backport to 3.13 bugs and security fixes label Dec 18, 2025
This was referenced Feb 17, 2026
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