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Title: gh-144981: Make PyUnstable_Code_SetExtra/GetExtra thread-safe by yoney · Pull Request #144980 · python/cpython · GitHub

Open Graph Title: gh-144981: Make PyUnstable_Code_SetExtra/GetExtra thread-safe by yoney · Pull Request #144980 · python/cpython

X Title: gh-144981: Make PyUnstable_Code_SetExtra/GetExtra thread-safe by yoney · Pull Request #144980 · python/cpython

Description: PyUnstable_Code_GetExtra and PyUnstable_Code_SetExtra had no thread-safety. Concurrent calls could cause data races. GetExtra is performance-sensitive for use cases like JIT. It uses a lock-free acquire load of co_extra, and acquire loads of individual slots. SetExtra uses a per-object critical section. When the slot already exists, it updates in place with a release store. When the buffer needs to grow, the free-threaded build allocates a new buffer, copies existing slots, publishes with a release store, and reclaims the old buffer via _PyMem_FreeDelayed(QSBR). The GIL build simply uses realloc. PyUnstable_Eval_RequestCodeExtraIndex is now protected by interp->code_state.mutex. Added free-threading tests for concurrent RequestCodeExtraIndex, SetExtra, and GetExtra. The new tests exercise the concurrent paths and a free-threaded TSAN build without the fix crashes/emits warnings. cc: @DinoV @colesbury Issue: gh-144981

Open Graph Description: PyUnstable_Code_GetExtra and PyUnstable_Code_SetExtra had no thread-safety. Concurrent calls could cause data races. GetExtra is performance-sensitive for use cases like JIT. It uses a lock-free ac...

X Description: PyUnstable_Code_GetExtra and PyUnstable_Code_SetExtra had no thread-safety. Concurrent calls could cause data races. GetExtra is performance-sensitive for use cases like JIT. It uses a lock-free ac...

Opengraph URL: https://github.com/python/cpython/pull/144980

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