New submission from Tomáš Jeziorský <galileo.gali...@seznam.cz>:

The following code is expected to fail:


import multiprocessing

def f(x):
        return x

if __name__ == '__main__':
        with multiprocessing.Pool(2, maxtasksperchild=0) as pool:
                pool.map(f, range(3))


since it uses a wrong value of the 'maxtasksperchild' parameter. I expect it to 
raise a ValueError but instead it starts to fill the stderr with practically 
endless traceback:


Process ForkPoolWorker-2:
Process ForkPoolWorker-1:
Traceback (most recent call last):
  File "/usr/lib/python3.6/multiprocessing/process.py", line 258, in _bootstrap
    self.run()
  File "/usr/lib/python3.6/multiprocessing/process.py", line 93, in run
    self._target(*self._args, **self._kwargs)
  File "/usr/lib/python3.6/multiprocessing/pool.py", line 95, in worker
    assert maxtasks is None or (type(maxtasks) == int and maxtasks > 0)
Traceback (most recent call last):
AssertionError
  File "/usr/lib/python3.6/multiprocessing/process.py", line 258, in _bootstrap
    self.run()
  File "/usr/lib/python3.6/multiprocessing/process.py", line 93, in run
    self._target(*self._args, **self._kwargs)
  File "/usr/lib/python3.6/multiprocessing/pool.py", line 95, in worker
    assert maxtasks is None or (type(maxtasks) == int and maxtasks > 0)
AssertionError
Process ForkPoolWorker-4:
Process ForkPoolWorker-3:
...


I don't think this is expected behavior.
Tested with Python 3.6.9 on Ubuntu 18.04.3.

----------
messages: 360872
nosy: jeyekomon
priority: normal
severity: normal
status: open
title: multiprocessing Pool maxtasksperchild=0 raises exception with endless 
traceback
type: behavior

_______________________________________
Python tracker <rep...@bugs.python.org>
<https://bugs.python.org/issue39477>
_______________________________________
_______________________________________________
Python-bugs-list mailing list
Unsubscribe: 
https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com

Reply via email to