https://github.com/python/cpython/commit/c476410dc5ae62ffb5e32f64f9a3a622485c7d93
commit: c476410dc5ae62ffb5e32f64f9a3a622485c7d93
branch: main
author: Sam Gross <colesb...@gmail.com>
committer: colesbury <colesb...@gmail.com>
date: 2025-03-07T09:58:09-05:00
summary:
gh-110206: Fix multiprocessing test_notify_all (#130933)
The test could deadlock trying join on the worker processes due to a
combination of behaviors:
* The use of `assertReachesEventually` did not ensure that workers
actually woken.release() because the SyncManager's Semaphore does not
implement get_value.
* This mean that the test could finish and the variable "sleeping" would
got out of scope and be collected. This unregisters the proxy leading
to failures in the worker or possibly the manager.
* The subsequent call to `p.join()` during cleanUp therefore never
finished.
This takes two approaches to fix this:
1) Use woken.acquire() to ensure that the workers actually finish
calling woken.release()
2) At the end of the test, wait until the workers are finished, while `cond`,
`sleeping`, and `woken` are still valid.
files:
M Lib/test/_test_multiprocessing.py
diff --git a/Lib/test/_test_multiprocessing.py
b/Lib/test/_test_multiprocessing.py
index 67ab8f098f700b..10c17b2dc7d32b 100644
--- a/Lib/test/_test_multiprocessing.py
+++ b/Lib/test/_test_multiprocessing.py
@@ -1694,18 +1694,19 @@ def test_notify_all(self):
woken = self.Semaphore(0)
# start some threads/processes which will timeout
+ workers = []
for i in range(3):
p = self.Process(target=self.f,
args=(cond, sleeping, woken, TIMEOUT1))
p.daemon = True
p.start()
- self.addCleanup(p.join)
+ workers.append(p)
t = threading.Thread(target=self.f,
args=(cond, sleeping, woken, TIMEOUT1))
t.daemon = True
t.start()
- self.addCleanup(t.join)
+ workers.append(t)
# wait for them all to sleep
for i in range(6):
@@ -1724,12 +1725,12 @@ def test_notify_all(self):
p = self.Process(target=self.f, args=(cond, sleeping, woken))
p.daemon = True
p.start()
- self.addCleanup(p.join)
+ workers.append(p)
t = threading.Thread(target=self.f, args=(cond, sleeping, woken))
t.daemon = True
t.start()
- self.addCleanup(t.join)
+ workers.append(t)
# wait for them to all sleep
for i in range(6):
@@ -1745,11 +1746,17 @@ def test_notify_all(self):
cond.release()
# check they have all woken
- self.assertReachesEventually(lambda: get_value(woken), 6)
+ for i in range(6):
+ woken.acquire()
+ self.assertReturnsIfImplemented(0, get_value, woken)
# check state is not mucked up
self.check_invariant(cond)
+ for w in workers:
+ # NOTE: join_process and join_thread are the same
+ threading_helper.join_thread(w)
+
def test_notify_n(self):
cond = self.Condition()
sleeping = self.Semaphore(0)
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