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Issue #8428: Fix a race condition in multiprocessing.Pool when terminating

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worker processes: new processes would be spawned while the pool is being
shut down.  Patch by Charles-François Natali.
This commit is contained in:
Antoine Pitrou 2011-04-11 00:26:42 +02:00
parent 04cb72f968
commit 7dfc874a48
2 changed files with 11 additions and 2 deletions
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9
Lib/multiprocessing/pool.py
View file

@ -295,6 +295,8 @@ class Pool(object):
while pool._worker_handler._state == RUN and pool._state == RUN: while pool._worker_handler._state == RUN and pool._state == RUN:
pool._maintain_pool() pool._maintain_pool()
time.sleep(0.1) time.sleep(0.1)
# send sentinel to stop workers
pool._taskqueue.put(None)
debug('worker handler exiting') debug('worker handler exiting')
@staticmethod @staticmethod
@ -413,7 +415,6 @@ class Pool(object):
if self._state == RUN: if self._state == RUN:
self._state = CLOSE self._state = CLOSE
self._worker_handler._state = CLOSE self._worker_handler._state = CLOSE
self._taskqueue.put(None)
def terminate(self): def terminate(self):
debug('terminating pool') debug('terminating pool')
@ -447,7 +448,6 @@ class Pool(object):
worker_handler._state = TERMINATE worker_handler._state = TERMINATE
task_handler._state = TERMINATE task_handler._state = TERMINATE
taskqueue.put(None) # sentinel
debug('helping task handler/workers to finish') debug('helping task handler/workers to finish')
cls._help_stuff_finish(inqueue, task_handler, len(pool)) cls._help_stuff_finish(inqueue, task_handler, len(pool))
@ -457,6 +457,11 @@ class Pool(object):
result_handler._state = TERMINATE result_handler._state = TERMINATE
outqueue.put(None) # sentinel outqueue.put(None) # sentinel
# We must wait for the worker handler to exit before terminating
# workers because we don't want workers to be restarted behind our back.
debug('joining worker handler')
worker_handler.join()
# Terminate workers which haven't already finished. # Terminate workers which haven't already finished.
if pool and hasattr(pool[0], 'terminate'): if pool and hasattr(pool[0], 'terminate'):
debug('terminating workers') debug('terminating workers')

4
Misc/NEWS
View file

@ -51,6 +51,10 @@ Core and Builtins
Library Library
------- -------
- Issue #8428: Fix a race condition in multiprocessing.Pool when terminating
worker processes: new processes would be spawned while the pool is being
shut down. Patch by Charles-François Natali.
- Issue #7311: fix HTMLParser to accept non-ASCII attribute values. - Issue #7311: fix HTMLParser to accept non-ASCII attribute values.
- Issue #10963: Ensure that subprocess.communicate() never raises EPIPE. - Issue #10963: Ensure that subprocess.communicate() never raises EPIPE.