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Data race: sys.addaudithook() lazily creates interp->audit_hooks with no lock #154431
Description
Bug report
Full report: https://gist.github.com/devdanzin/0b13838fd6089e73a3f063ed8f68e733
Repro:
import sys, threading
assert not sys._is_gil_enabled(), "run free-threaded: PYTHON_GIL=0"
NADD = 24 # threads slamming the first-time lazy-init store (write @540) at once
NAUD = 8 # threads spinning audit events (should_audit read @239)
barrier = threading.Barrier(NADD + NAUD)
def _hook(*a):
return None
def adder():
barrier.wait()
for _ in range(200):
sys.addaudithook(_hook) # write interp->audit_hooks (first time) @540
def auditor():
barrier.wait()
for _ in range(200000):
sys.audit("fusil.tsan.test") # should_audit read of interp->audit_hooks @239
ts = [threading.Thread(target=adder) for _ in range(NADD)]
ts += [threading.Thread(target=auditor) for _ in range(NAUD)]
for t in ts: t.start()
for t in ts: t.join()
print("done, no crash")The fix is incoming.
Linked PRs
- gh-154431: Fix data race in
sys.audithook#154462 - [3.15] gh-154431: Fix data race in
sys.audithook(GH-154462) #154477 - [3.14] gh-154431: Fix data race in
sys.audithook(GH-154462) #154478 - gh-154431: Use existing
runtime->audit_hooks.mutexinstead of a new one #154494 - gh-154431: Eagerly initialize the audit hooks list #154554
- gh-154431: Revert "gh-154431: Fix data race in
sys.audithook(#154462)" #154769 - [3.15] gh-154431: Revert "gh-154431: Fix data race in
sys.audithook(GH-154462)" (GH-154769) #154774
Activity
pythongh-154431: Fix data race in `sys.audithook`
gh-154431: Fix data race in `sys.audithook` (#154462)
[3.15] gh-154431: Fix data race in `sys.audithook` (GH-154462) (#154477)
gh-154431: Revert "gh-154431: Fix data race in `sys.audithook` (#154462…
encukou commentedon Jul 27, 2026
The commit caused a refleak that made tier 1 buildbot fail (e.g. [here](e.g. https://buildbot.python.org/#/builders/1610/builds/3726)); it was failing throughout the weekend. I've reverted to get the CI green.
Please add the change itself (an un-revert) to the follow-up PR(s). Let me know if you want assistance.
Merge branch 'main' into issues/pythongh-154431-sys-addaudithook-race
[3.15] gh-154431: Revert "gh-154431: Fix data race in `sys.audithook` (…
pythongh-154431: Revert "pythongh-154431: Fix data race in `sys.audit…
Merge branch 'main' into issues/pythongh-154431-sys-addaudithook-race