bpo-29293: multiprocessing.Condition.notify() lacks parameter `n` (#2480)
* bpo-29293: multiprocessing.Condition.notify() lacks parameter `n` * Add NEWS blurb
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@ -999,8 +999,8 @@ class ConditionProxy(AcquirerProxy):
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_exposed_ = ('acquire', 'release', 'wait', 'notify', 'notify_all')
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def wait(self, timeout=None):
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return self._callmethod('wait', (timeout,))
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def notify(self):
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return self._callmethod('notify')
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def notify(self, n=1):
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return self._callmethod('notify', (n,))
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def notify_all(self):
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return self._callmethod('notify_all')
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def wait_for(self, predicate, timeout=None):
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@ -268,24 +268,7 @@ class Condition(object):
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for i in range(count):
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self._lock.acquire()
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def notify(self):
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assert self._lock._semlock._is_mine(), 'lock is not owned'
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assert not self._wait_semaphore.acquire(False)
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# to take account of timeouts since last notify() we subtract
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# woken_count from sleeping_count and rezero woken_count
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while self._woken_count.acquire(False):
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res = self._sleeping_count.acquire(False)
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assert res
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if self._sleeping_count.acquire(False): # try grabbing a sleeper
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self._wait_semaphore.release() # wake up one sleeper
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self._woken_count.acquire() # wait for the sleeper to wake
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# rezero _wait_semaphore in case a timeout just happened
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self._wait_semaphore.acquire(False)
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def notify_all(self):
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def notify(self, n=1):
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assert self._lock._semlock._is_mine(), 'lock is not owned'
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assert not self._wait_semaphore.acquire(False)
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@ -296,7 +279,7 @@ class Condition(object):
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assert res
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sleepers = 0
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while self._sleeping_count.acquire(False):
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while sleepers < n and self._sleeping_count.acquire(False):
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self._wait_semaphore.release() # wake up one sleeper
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sleepers += 1
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@ -308,6 +291,9 @@ class Condition(object):
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while self._wait_semaphore.acquire(False):
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pass
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def notify_all(self):
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self.notify(n=sys.maxsize)
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def wait_for(self, predicate, timeout=None):
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result = predicate()
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if result:
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@ -948,6 +948,17 @@ class _TestCondition(BaseTestCase):
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woken.release()
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cond.release()
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def assertReachesEventually(self, func, value):
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for i in range(10):
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try:
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if func() == value:
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break
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except NotImplementedError:
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break
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time.sleep(DELTA)
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time.sleep(DELTA)
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self.assertReturnsIfImplemented(value, func)
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def check_invariant(self, cond):
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# this is only supposed to succeed when there are no sleepers
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if self.TYPE == 'processes':
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@ -1055,13 +1066,54 @@ class _TestCondition(BaseTestCase):
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cond.release()
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# check they have all woken
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for i in range(10):
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try:
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if get_value(woken) == 6:
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break
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except NotImplementedError:
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break
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time.sleep(DELTA)
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self.assertReachesEventually(lambda: get_value(woken), 6)
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# check state is not mucked up
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self.check_invariant(cond)
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def test_notify_n(self):
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cond = self.Condition()
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sleeping = self.Semaphore(0)
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woken = self.Semaphore(0)
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# start some threads/processes
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for i in range(3):
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p = self.Process(target=self.f, args=(cond, sleeping, woken))
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p.daemon = True
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p.start()
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t = threading.Thread(target=self.f, args=(cond, sleeping, woken))
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t.daemon = True
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t.start()
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# wait for them to all sleep
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for i in range(6):
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sleeping.acquire()
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# check no process/thread has woken up
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time.sleep(DELTA)
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self.assertReturnsIfImplemented(0, get_value, woken)
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# wake some of them up
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cond.acquire()
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cond.notify(n=2)
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cond.release()
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# check 2 have woken
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self.assertReachesEventually(lambda: get_value(woken), 2)
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# wake the rest of them
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cond.acquire()
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cond.notify(n=4)
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cond.release()
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self.assertReachesEventually(lambda: get_value(woken), 6)
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# doesn't do anything more
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cond.acquire()
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cond.notify(n=3)
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cond.release()
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self.assertReturnsIfImplemented(6, get_value, woken)
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# check state is not mucked up
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@ -0,0 +1,5 @@
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Add missing parameter "n" on multiprocessing.Condition.notify().
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The doc claims multiprocessing.Condition behaves like threading.Condition,
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but its notify() method lacked the optional "n" argument (to specify the
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number of sleepers to wake up) that threading.Condition.notify() accepts.
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