I gave my Windows buildbots a little bit of TLC last night. This little
chestnut in test_multiprocessing.py around line 1346 is causing my buildbots to
wedge more often than not:
def test_listener_client(self):
for family in self.connection.families:
l = self.connection.Listener(family=family)
p = self.Process(target=self._test, args=(l.address,))
p.set_daemon(True)
p.start()
conn = l.accept()
self.assertEqual(conn.recv(), 'hello')
p.join()
l.close()
The wedging will be a result of that accept() call. Not knowing anything about
the module or the test suite, I can only assume that there's a race condition
introduced between when the subprocess attempts to connect to the listener,
versus when the l.accept() call is actually entered. (On the basis that a race
condition would explain why sometimes it wedges and sometimes it doesn't.)
Just FYI, the error in the buildbot log
(http://www.python.org/dev/buildbot/all/x86%20W2k8%20trunk/builds/810/step-test/0)
when this occurs is as follows:
test_multiprocessing
command timed out: 1200 seconds without output
SIGKILL failed to kill process
using fake rc=-1
program finished with exit code -1
remoteFailed: [Failure instance: Traceback from remote host -- Traceback (most
recent call last):
Failure: buildbot.slave.commands.TimeoutError: SIGKILL failed to kill process
]
(The fact it can't be killed cleanly is a bug in Twisted's
signalProcess('KILL') method, which doesn't work against Python processes that
have entered accept() calls on Windows (which present the 'wedged' behaviour
and have to be forcibly killed with OpenProcess/TerminateProcess).)
Trent.
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