Issue #8799: Reduce timing sensitivity of condition test by explicitly

delaying the main thread so that it doesn't race ahead of the workers.
This commit is contained in:
Kristjan Valur Jonsson 2013-11-11 11:29:04 +00:00
parent 23a7827c45
commit 020af2a2bc
1 changed files with 15 additions and 0 deletions

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@ -418,6 +418,17 @@ class ConditionTests(BaseTestCase):
self.assertRaises(RuntimeError, cond.notify)
def _check_notify(self, cond):
# Note that this test is sensitive to timing. If the worker threads
# don't execute in a timely fashion, the main thread may think they
# are further along then they are. The main thread therefore issues
# _wait() statements to try to make sure that it doesn't race ahead
# of the workers.
# Secondly, this test assumes that condition variables are not subject
# to spurious wakeups. The absence of spurious wakeups is an implementation
# detail of Condition Cariables in current CPython, but in general, not
# a guaranteed property of condition variables as a programming
# construct. In particular, it is possible that this can no longer
# be conveniently guaranteed should their implementation ever change.
N = 5
results1 = []
results2 = []
@ -445,6 +456,9 @@ class ConditionTests(BaseTestCase):
_wait()
self.assertEqual(results1, [(True, 1)] * 3)
self.assertEqual(results2, [])
# first wait, to ensure all workers settle into cond.wait() before
# we continue. See issue #8799
_wait()
# Notify 5 threads: they might be in their first or second wait
cond.acquire()
cond.notify(5)
@ -455,6 +469,7 @@ class ConditionTests(BaseTestCase):
_wait()
self.assertEqual(results1, [(True, 1)] * 3 + [(True, 2)] * 2)
self.assertEqual(results2, [(True, 2)] * 3)
_wait() # make sure all workers settle into cond.wait()
# Notify all threads: they are all in their second wait
cond.acquire()
cond.notify_all()