Issue #11867: Make test_mailbox.test_lock_conflict deterministic (and fix a

race condition).
This commit is contained in:
Charles-François Natali 2011-12-19 12:17:16 +01:00
parent 6b7003a18c
commit 52aa260387
1 changed files with 26 additions and 12 deletions

View File

@ -15,6 +15,10 @@ try:
import fcntl
except ImportError:
pass
try:
import multiprocessing
except ImportError:
multiprocessing = None
# Silence Py3k warning
rfc822 = test_support.import_module('rfc822', deprecated=True)
@ -865,26 +869,36 @@ 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.
self._box.lock()
time.sleep(2)
self._box.unlock()
os._exit(0)
# child
try:
# lock the mailbox, and signal the parent it can proceed
self._box.lock()
ready.set()
# In the parent, sleep a bit to give the child time to acquire
# the lock.
time.sleep(0.5)
# wait until the parent is done, and unlock the mailbox
done.wait(5)
self._box.unlock()
finally:
os._exit(0)
# 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)