https://github.com/python/cpython/commit/6a02a8848fece567d97810b170b7e5e8ce36813a commit: 6a02a8848fece567d97810b170b7e5e8ce36813a branch: 3.14 author: Miss Islington (bot) <[email protected]> committer: kumaraditya303 <[email protected]> date: 2026-06-03T11:54:42Z summary:
[3.14] gh-148613: Fix race in `gc_set_threshold` and `gc_get_threshold` (GH-150356) (#150842) gh-148613: Fix race in `gc_set_threshold` and `gc_get_threshold` (GH-150356) (cherry picked from commit 41eb8ee2bb8cfd4129736e1f6068e702b8bdba6c) Co-authored-by: Edward Xu <[email protected]> files: A Misc/NEWS.d/next/Core_and_Builtins/2026-05-24-22-46-49.gh-issue-148613.PLpmyd.rst M Lib/test/test_free_threading/test_gc.py M Modules/gcmodule.c diff --git a/Lib/test/test_free_threading/test_gc.py b/Lib/test/test_free_threading/test_gc.py index 8b45b6e2150c288..cc1888dae48bc03 100644 --- a/Lib/test/test_free_threading/test_gc.py +++ b/Lib/test/test_free_threading/test_gc.py @@ -94,6 +94,36 @@ def evil(): thread.start() thread.join() + def test_set_threshold(self): + # GH-148613: Setting the GC threshold from another thread could cause a + # race between the `gc_should_collect` and `gc_set_threshold` functions. + NUM_THREADS = 8 + NUM_ITERS = 100_000 + barrier = threading.Barrier(NUM_THREADS) + + class CyclicReference: + def __init__(self): + self.r = self + + def allocator(): + barrier.wait() + for _ in range(NUM_ITERS): + CyclicReference() + + def setter(): + barrier.wait() + for i in range(NUM_ITERS): + gc.set_threshold(100 + (i % 100), 10 + (i % 10), 10 + (i % 10)) + + current_threshold = gc.get_threshold() + try: + threads = [Thread(target=allocator) for _ in range(NUM_THREADS - 1)] + threads.append(Thread(target=setter)) + with threading_helper.start_threads(threads): + pass + finally: + gc.set_threshold(*current_threshold) + if __name__ == "__main__": unittest.main() diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2026-05-24-22-46-49.gh-issue-148613.PLpmyd.rst b/Misc/NEWS.d/next/Core_and_Builtins/2026-05-24-22-46-49.gh-issue-148613.PLpmyd.rst new file mode 100644 index 000000000000000..71a701bf3eb3551 --- /dev/null +++ b/Misc/NEWS.d/next/Core_and_Builtins/2026-05-24-22-46-49.gh-issue-148613.PLpmyd.rst @@ -0,0 +1,2 @@ +Fix a data race in the free-threaded build between :func:`gc.set_threshold` +and garbage collection scheduling during object allocation. diff --git a/Modules/gcmodule.c b/Modules/gcmodule.c index 2a2ce72f82c78eb..fe1802c73dab315 100644 --- a/Modules/gcmodule.c +++ b/Modules/gcmodule.c @@ -168,6 +168,8 @@ gc_set_threshold_impl(PyObject *module, int threshold0, int group_right_1, gcstate->generations[2].threshold = threshold2; } #else + PyInterpreterState *interp = _PyInterpreterState_GET(); + _PyEval_StopTheWorld(interp); gcstate->young.threshold = threshold0; if (group_right_1) { gcstate->old[0].threshold = threshold1; @@ -175,6 +177,7 @@ gc_set_threshold_impl(PyObject *module, int threshold0, int group_right_1, if (group_right_2) { gcstate->old[1].threshold = threshold2; } + _PyEval_StartTheWorld(interp); #endif Py_RETURN_NONE; } _______________________________________________ Python-checkins mailing list -- [email protected] To unsubscribe send an email to [email protected] https://mail.python.org/mailman3//lists/python-checkins.python.org Member address: [email protected]
