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authorCharles-François Natali <neologix@free.fr>2011-12-19 11:18:55 (GMT)
committerCharles-François Natali <neologix@free.fr>2011-12-19 11:18:55 (GMT)
commit78ed83da46b4f87e6e04a15f4d330ccb28274d03 (patch)
tree4e121b1391e8c30779f6bf394a3ee6bbc1e3bc92 /Lib
parent62f3d0300ebfd00167d7221153c3ddb7accd4cbd (diff)
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Issue #11867: Make test_mailbox.test_lock_conflict deterministic (and fix a
race condition).
Diffstat (limited to 'Lib')
-rw-r--r--Lib/test/test_mailbox.py30
1 files changed, 21 insertions, 9 deletions
diff --git a/Lib/test/test_mailbox.py b/Lib/test/test_mailbox.py
index 007c419..720eb6f 100644
--- a/Lib/test/test_mailbox.py
+++ b/Lib/test/test_mailbox.py
@@ -17,6 +17,10 @@ try:
import fcntl
except ImportError:
pass
+try:
+ import multiprocessing
+except ImportError:
+ multiprocessing = None
class TestBase(unittest.TestCase):
@@ -994,28 +998,36 @@ class _TestMboxMMDF(TestMailbox):
self.assertEqual(contents, f.read())
self._box = self._factory(self._path)
+ @unittest.skipUnless(hasattr(os, 'fork'), "Test needs fork().")
+ @unittest.skipUnless(multiprocessing, "Test needs multiprocessing.")
def test_lock_conflict(self):
- # Fork off a subprocess that will lock the file for 2 seconds,
- # unlock it, and then exit.
- if not hasattr(os, 'fork'):
- return
+ # Fork off a child process that will lock the mailbox temporarily,
+ # unlock it and exit.
+ ready = multiprocessing.Event()
+ done = multiprocessing.Event()
+
pid = os.fork()
if pid == 0:
- # In the child, lock the mailbox.
+ # child
try:
+ # lock the mailbox, and signal the parent it can proceed
self._box.lock()
- time.sleep(2)
+ ready.set()
+
+ # wait until the parent is done, and unlock the mailbox
+ done.wait(5)
self._box.unlock()
finally:
os._exit(0)
- # In the parent, sleep a bit to give the child time to acquire
- # the lock.
- time.sleep(0.5)
+ # In the parent, wait until the child signals it locked the mailbox.
+ ready.wait(5)
try:
self.assertRaises(mailbox.ExternalClashError,
self._box.lock)
finally:
+ # Signal the child it can now release the lock and exit.
+ done.set()
# Wait for child to exit. Locking should now succeed.
exited_pid, status = os.waitpid(pid, 0)