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bpo-33078 - FIX queue size on pickling error #6119

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Merged
pitrou merged 4 commits into from
Mar 21, 2018
Merged

bpo-33078 - FIX queue size on pickling error #6119

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4b3e3fa
FIX properly handle queue size in on error
tomMoral Mar 15, 2018
36087a5
TST add non regression test
tomMoral Mar 15, 2018
e5a127c
DOC add NEWS entry
tomMoral Mar 15, 2018
747b3ab
CLN typo and comments
tomMoral Mar 21, 2018
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10 changes: 8 additions & 2 deletions Lib/multiprocessing/queues.py
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Original file line number Diff line number Diff line change
Expand Up @@ -161,7 +161,7 @@ def _start_thread(self):
target=Queue._feed,
args=(self._buffer, self._notempty, self._send_bytes,
self._wlock, self._writer.close, self._ignore_epipe,
self._on_queue_feeder_error),
self._on_queue_feeder_error, self._sem),
name='QueueFeederThread'
)
self._thread.daemon = True
Expand Down Expand Up @@ -203,7 +203,7 @@ def _finalize_close(buffer, notempty):

@staticmethod
def _feed(buffer, notempty, send_bytes, writelock, close, ignore_epipe,
onerror):
onerror, queue_sem):
debug('starting thread to feed data to pipe')
nacquire = notempty.acquire
nrelease = notempty.release
Expand Down Expand Up @@ -255,6 +255,12 @@ def _feed(buffer, notempty, send_bytes, writelock, close, ignore_epipe,
info('error in queue thread: %s', e)
return
else:
# Since the object has not been sent in the queue, we need
# to decrease the size of the queue. The error acts as
# if the object had been silently removed from the queue
# and this step is necessary to have a properly working
# queue.
queue_sem.release()
onerror(e, obj)

@staticmethod
Expand Down
13 changes: 13 additions & 0 deletions Lib/test/_test_multiprocessing.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1056,6 +1056,19 @@ def __reduce__(self):
self.assertTrue(q.get(timeout=1.0))
close_queue(q)

with test.support.captured_stderr():
# bpo-33078: verify that the queue size is correctly handled
# on errors.
q = self.Queue(maxsize=1)
q.put(NotSerializable())
q.put(True)
self.assertEqual(q.qsize(), 1)

@pitrou pitrou Mar 21, 2018

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Is this check correct? Depending on when the worker thread triggers, it might return 2, no?

@tomMoral tomMoral Mar 21, 2018

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I think it is correct because maxsize=1 so the second q.put should return only once the failure has been triggered.

@pitrou pitrou Mar 21, 2018

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That's a good point, thank you.

# bpo-30595: use a timeout of 1 second for slow buildbots
self.assertTrue(q.get(timeout=1.0))
# Check that the size of the queue is correct
self.assertEqual(q.qsize(), 0)
close_queue(q)

def test_queue_feeder_on_queue_feeder_error(self):
# bpo-30006: verify feeder handles exceptions using the
# _on_queue_feeder_error hook.
Expand Down
2 changes: 2 additions & 0 deletions Misc/NEWS.d/next/Library/2018-03-15-07-38-00.bpo-33078.RmjUF5.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1,2 @@
Fix the size handling in multiprocessing.Queue when a pickling error
occurs.