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bpo-40221: Update multiprocessing to use _at_fork_reinit #19511

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Merged
merged 2 commits into from
Apr 14, 2020
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bpo-40221: Update multiprocessing to use _at_fork_reinit #19511

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7121b4a
bpo-40221: Update multiprocessing to use _at_fork_reinit
corona10 Apr 14, 2020
fe3f6e3
bpo-40221: Apply code review
corona10 Apr 14, 2020
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13 changes: 9 additions & 4 deletions Lib/multiprocessing/queues.py
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Original file line number Diff line number Diff line change
Expand Up @@ -49,8 +49,7 @@ def __init__(self, maxsize=0, *, ctx):
self._sem = ctx.BoundedSemaphore(maxsize)
# For use by concurrent.futures
self._ignore_epipe = False

self._after_fork()
self._reset()

if sys.platform != 'win32':
register_after_fork(self, Queue._after_fork)
Expand All @@ -63,11 +62,17 @@ def __getstate__(self):
def __setstate__(self, state):
(self._ignore_epipe, self._maxsize, self._reader, self._writer,
self._rlock, self._wlock, self._sem, self._opid) = state
self._after_fork()
self._reset()

def _after_fork(self):
debug('Queue._after_fork()')
self._notempty = threading.Condition(threading.Lock())
self._reset(after_fork=True)

def _reset(self, after_fork=False):
if after_fork:
self._notempty._at_fork_reinit()
else:
self._notempty = threading.Condition(threading.Lock())
self._buffer = collections.deque()
self._thread = None
self._jointhread = None
Expand Down
6 changes: 1 addition & 5 deletions Lib/multiprocessing/resource_sharer.py
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Expand Up @@ -63,7 +63,6 @@ class _ResourceSharer(object):
def __init__(self):
self._key = 0
self._cache = {}
self._old_locks = []
self._lock = threading.Lock()
self._listener = None
self._address = None
Expand Down Expand Up @@ -113,10 +112,7 @@ def _afterfork(self):
for key, (send, close) in self._cache.items():
close()
self._cache.clear()
# If self._lock was locked at the time of the fork, it may be broken
# -- see issue 6721. Replace it without letting it be gc'ed.
self._old_locks.append(self._lock)
self._lock = threading.Lock()
self._lock._at_fork_reinit()
if self._listener is not None:
self._listener.close()
self._listener = None
Expand Down