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gh-144356: fix data race in`setiter_len()` under no-gil#144357

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gh-144356: fix data race in`setiter_len()` under no-gil#144357

hyongtao-code wants to merge3 commits intopython:mainfromhyongtao-code:fix-data-race

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hyongtao-code commentedJan 31, 2026•
edited by bedevere-appbot
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Long log:

setiter_len() was readingso->used without atomic access while concurrent
mutations update it atomically under Py_GIL_DISABLED.

Use an atomic load forso->used to avoid a data race. This preserves the
existing semantics of__length_hint__ while making the access thread-safe.

Signed-off-by: Yongtao Huangyongtaoh2022@gmail.com

Issue:Data race in set iterator length_hint under no-gil #144356

hyongtao-code added2 commits

January 31, 2026 10:51

Fix data race in setiter_len() under no-gil

47d75fe

setiter_len() was reading so->used without atomic access while concurrentmutations update it atomically under Py_GIL_DISABLED.Use an atomic load for so->used to avoid a data race. This preserves theexisting semantics of __length_hint__ while making the access thread-safe.Signed-off-by: Yongtao Huang <yongtaoh2022@gmail.com>

Add test case

3e3785c