[3.13] gh-126914: Store the Preallocated Thread State's Pointer in a PyInterpreterState Field#127114
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…yInterpreterState Field (pythongh-126989) This approach eliminates the originally reported race. It also gets rid of the deadlock reported in pythongh-96071, so we can remove the workaround added then.
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ericsnowcurrently commented Nov 21, 2024
@Yhg1s, this changes only internal ABI, so we should be fine updating the ABI data file, right? |
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Yhg1s commented Nov 25, 2024
Yes, the struct is always allocated by the runtime, and the new field is used only by the runtime, never extension modules, so updating the ABI definition is fine. |
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Yhg1s commented Dec 2, 2024
Do you want to get this into 3.13.1? (It's scheduled for tomorrow :) |
ericsnowcurrently merged commit 219b826 into python:3.13 33 checks passed
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colesbury added a commit to colesbury/cpython that referenced this pull request Apr 1, 2025
The 3.13 free threaded build immortalizes certain objects to avoid reference count contention. In pythongh-127114 the condition was unintentionally changed to happen when the first thread was created instead of the first non-main thread. The `interp->gc.immortalize` field is then cleared again during `_PyGC_Init()`. Change the condition so that we check if we should immortalize objects using deferred reference counting whenever a non-main thread is created.
Yhg1s pushed a commit that referenced this pull request Apr 7, 2025
gh-131988: Fix a multithreaded scaling regression The 3.13 free threaded build immortalizes certain objects to avoid reference count contention. In gh-127114 the condition was unintentionally changed to happen when the first thread was created instead of the first non-main thread. The `interp->gc.immortalize` field is then cleared again during `_PyGC_Init()`. Change the condition so that we check if we should immortalize objects using deferred reference counting whenever a non-main thread is created.
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This approach eliminates the originally reported race. It also gets rid of the deadlock reported in gh-96071, so we can remove the workaround added then.
This is mostly a cherry-pick of 1c0a104 (AKA gh-126989). The difference is we add
PyInterpreterState.threads_preallocatedat the end ofPyInterpreterState, instead of addingPyInterpreterState.threads.preallocated. That avoids ABI disruption.