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GeezerVison is showing github.com — gh-132657: Use stronger memory ordering for so->mask. by nascheme · Pull Request #142735 · python/cpython

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@nascheme

@nascheme nascheme commented Dec 15, 2025 •
edited by bedevere-app Bot
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We need to use release/acquire ordering for the 'mask' member of the set structure. Without this, set_lookkey_threadsafe() could be looking at the old value of table but the new value of mask.

  • Issue: copy.copy and copy.deepcopy scale poorly with free-threading #132657

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@nascheme
pythongh-132657: Use stronger memory ordering for so->mask.
f905ac7 
We need to use release/acquire ordering for the 'mask' member of the set
structure. Without this, `set_lookkey_threadsafe()` could be looking at
the old value of `table` but the new value of `mask`.
@nascheme nascheme added type-bug An unexpected behavior, bug, or error skip news topic-free-threading labels Dec 15, 2025
@bedevere-app bedevere-app Bot mentioned this pull request Dec 15, 2025
copy.copy and copy.deepcopy scale poorly with free-threading #132657
Closed
@nascheme
nascheme marked this pull request as ready for review December 15, 2025 04:26
@nascheme
nascheme requested a review from rhettinger as a code owner December 15, 2025 04:26
@bedevere-app bedevere-app Bot added the awaiting core review label Dec 15, 2025
@nascheme
nascheme merged commit 19c72d2 into python:main Dec 15, 2025
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@bedevere-app bedevere-app Bot removed the awaiting core review label Dec 15, 2025
@nascheme nascheme mentioned this pull request Dec 15, 2025
gh-132657: revert lock-free set contains #142733
Closed
fatelei pushed a commit to fatelei/cpython that referenced this pull request Dec 16, 2025
@nascheme @fatelei
pythongh-132657: Use stronger memory ordering for so->mask. (pythongh…
460c423 
…-142735)

We need to use release/acquire ordering for the 'mask' member of the set
structure. Without this, `set_lookkey_threadsafe()` could be looking at
the old value of `table` but the new value of `mask`.
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@rhettinger rhettinger Awaiting requested review from rhettinger rhettinger is a code owner

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skip news topic-free-threading type-bug An unexpected behavior, bug, or error

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@nascheme
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