GeezerVison is showing github.com — [3.14] gh-159739: Hold the codec registry lock while unregistering (GH-160168) by jelle-openai · Pull Request #160485 · python/cpython
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Oct 23, 2026
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Concurrent calls to codecs.unregister() can shrink the search path between its length check and indexed lookup in a free-threaded build. The lookup then returns NULL and an unconditional decref crashes the interpreter; hold the registry mutex across the scan and removal. Also reported in gh-157078. Backport to 3.15 and 3.14.
(cherry picked from commit 784b305)
Co-authored-by: Jelle Zijlstra [email protected]
Backport of #160168 to 3.14.
Hold 3.14's codec search-path mutex across the length check, lookup, and removal. Release it before dropping the temporary reference.
Ran test_codecs on a free-threaded 3.14 build. Eight threads completed 102,400 register/unregister pairs with the GIL disabled.
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…ing (pythonGH-160168)
Concurrent calls to codecs.unregister() can shrink the search path between its length check and indexed lookup in a free-threaded build. The lookup then returns NULL and an unconditional decref crashes the interpreter; hold the registry mutex across the scan and removal. Also reported in pythongh-157078. Backport to 3.15 and 3.14.
(cherry picked from commit 784b305)
Co-authored-by: Jelle Zijlstra <[email protected]>
This was referenced Oct 23, 2026
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