[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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@Yhg1s, this changes only internal ABI, so we should be fine updating the ABI data file, right? |
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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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Do you want to get this into 3.13.1? (It's scheduled for tomorrow :) |
colesbury
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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
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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.