From 7dfc874a48516e58e830b3a455fca34c8cd834eb Mon Sep 17 00:00:00 2001 From: Antoine Pitrou Date: Mon, 11 Apr 2011 00:26:42 +0200 Subject: [PATCH] =?utf8?q?Issue=20#8428:=20Fix=20a=20race=20condition=20in?= =?utf8?q?=20multiprocessing.Pool=20when=20terminating=20worker=20processe?= =?utf8?q?s:=20new=20processes=20would=20be=20spawned=20while=20the=20pool?= =?utf8?q?=20is=20being=20shut=20down.=20=20Patch=20by=20Charles-Fran?= =?utf8?q?=C3=A7ois=20Natali.?= MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit --- Lib/multiprocessing/pool.py | 9 +++++++-- Misc/NEWS | 4 ++++ 2 files changed, 11 insertions(+), 2 deletions(-) diff --git a/Lib/multiprocessing/pool.py b/Lib/multiprocessing/pool.py index 1f366f035e..862a60e92c 100644 --- a/Lib/multiprocessing/pool.py +++ b/Lib/multiprocessing/pool.py @@ -295,6 +295,8 @@ class Pool(object): while pool._worker_handler._state == RUN and pool._state == RUN: pool._maintain_pool() time.sleep(0.1) + # send sentinel to stop workers + pool._taskqueue.put(None) debug('worker handler exiting') @staticmethod @@ -413,7 +415,6 @@ class Pool(object): if self._state == RUN: self._state = CLOSE self._worker_handler._state = CLOSE - self._taskqueue.put(None) def terminate(self): debug('terminating pool') @@ -447,7 +448,6 @@ class Pool(object): worker_handler._state = TERMINATE task_handler._state = TERMINATE - taskqueue.put(None) # sentinel debug('helping task handler/workers to finish') cls._help_stuff_finish(inqueue, task_handler, len(pool)) @@ -457,6 +457,11 @@ class Pool(object): result_handler._state = TERMINATE 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. if pool and hasattr(pool[0], 'terminate'): debug('terminating workers') diff --git a/Misc/NEWS b/Misc/NEWS index ee75bdad2c..5eb38dabd8 100644 --- a/Misc/NEWS +++ b/Misc/NEWS @@ -51,6 +51,10 @@ Core and Builtins 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 #10963: Ensure that subprocess.communicate() never raises EPIPE. -- 2.40.0