Issue #11867: Make test_mailbox.test_lock_conflict deterministic (and fix a
race condition).
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@ -15,6 +15,10 @@ try:
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import fcntl
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except ImportError:
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pass
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try:
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import multiprocessing
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except ImportError:
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multiprocessing = None
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# Silence Py3k warning
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rfc822 = test_support.import_module('rfc822', deprecated=True)
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@ -865,26 +869,36 @@ class _TestMboxMMDF(TestMailbox):
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self.assertEqual(contents, f.read())
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self._box = self._factory(self._path)
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@unittest.skipUnless(hasattr(os, 'fork'), "Test needs fork().")
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@unittest.skipUnless(multiprocessing, "Test needs multiprocessing.")
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def test_lock_conflict(self):
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# Fork off a subprocess that will lock the file for 2 seconds,
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# unlock it, and then exit.
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if not hasattr(os, 'fork'):
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return
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# Fork off a child process that will lock the mailbox temporarily,
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# unlock it and exit.
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ready = multiprocessing.Event()
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done = multiprocessing.Event()
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pid = os.fork()
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if pid == 0:
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# In the child, lock the mailbox.
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self._box.lock()
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time.sleep(2)
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self._box.unlock()
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os._exit(0)
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# child
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try:
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# lock the mailbox, and signal the parent it can proceed
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self._box.lock()
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ready.set()
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# In the parent, sleep a bit to give the child time to acquire
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# the lock.
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time.sleep(0.5)
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# wait until the parent is done, and unlock the mailbox
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done.wait(5)
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self._box.unlock()
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finally:
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os._exit(0)
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# In the parent, wait until the child signals it locked the mailbox.
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ready.wait(5)
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try:
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self.assertRaises(mailbox.ExternalClashError,
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self._box.lock)
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finally:
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# Signal the child it can now release the lock and exit.
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done.set()
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# Wait for child to exit. Locking should now succeed.
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exited_pid, status = os.waitpid(pid, 0)
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