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Author ahcub
Recipients ahcub
Date 2018-09-01.16:52:43
SpamBayes Score -1.0
Marked as misclassified Yes
Message-id <>
the bug is reproduced on big multiprocessing.Process output
when the size of the output gets bigger than signed int the value becomes negative, thus
assert left > 0
in multiprocessing/ raises an exception like the following

Traceback (most recent call last):
  File "D:\GitHub\cpython\lib\", line 917, in _bootstrap_inner
  File "D:\GitHub\cpython\lib\", line 865, in run
    self._target(*self._args, **self._kwargs)
  File "D:\GitHub\cpython\lib\multiprocessing\", line 470, in _handle_results
    task = get()
  File "D:\GitHub\cpython\lib\multiprocessing\", line 250, in recv
    buf = self._recv_bytes()
  File "D:\GitHub\cpython\lib\multiprocessing\", line 318, in _recv_bytes
    return self._get_more_data(ov, maxsize)
  File "D:\GitHub\cpython\lib\multiprocessing\", line 337, in _get_more_data
    assert left > 0

this assert looks invalid in this case because in C code the left value is DWORD (unsigned long), which cannot be negative by definition.
Date User Action Args
2018-09-01 16:52:43ahcubsetrecipients: + ahcub
2018-09-01 16:52:43ahcubsetmessageid: <>
2018-09-01 16:52:43ahcublinkissue34563 messages
2018-09-01 16:52:43ahcubcreate