bpo-39776: Lock ++interp->tstate_next_unique_id (GH-18746) · python/cpython@852aee6 (original) (raw)

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Misc/NEWS.d/next/Core and Builtins

2 files changed

lines changed

Original file line number	Diff line number	Diff line change
@@ -0,0 +1,6 @@
	1	+Fix race condition where threads created by PyGILState_Ensure() could get a
	2	+duplicate id.
	3	+
	4	+This affects consumers of tstate->id like the contextvar caching machinery,
	5	+which could return invalid cached objects under heavy thread load (observed
	6	+in embedded scenarios).

Original file line number	Diff line number	Diff line change
@@ -411,12 +411,12 @@ new_threadstate(PyInterpreterState *interp, int init)
411	411	tstate->context = NULL;
412	412	tstate->context_ver = 1;
413	413
414		-tstate->id = ++interp->tstate_next_unique_id;
415	414
416	415	if (init)
417	416	_PyThreadState_Init(tstate);
418	417
419	418	HEAD_LOCK();
	419	+tstate->id = ++interp->tstate_next_unique_id;
420	420	tstate->prev = NULL;
421	421	tstate->next = interp->tstate_head;
422	422	if (tstate->next)