multiprocessing and Locks
Piet van Oostrum
piet at cs.uu.nl
Sun Apr 12 13:30:56 EDT 2009
>>>>> gvv <gvverdad at gmail.com> (G) wrote:
>G> Hi All,
>G> I am trying to understand multiprocessing, but I am getting a Runtime
>G> error on the
>G> code below. What am I missing or doing wrong?
>G> Error is:
>G> RuntimeError: Lock objects should only be shared between processes
>G> through inheritance
[code deleted]
I guess you can't share locks (and probably other objects) between
processes from a Pool. Maybe because there is no direct parent-child
relation or so (there is a separate thread involved). There is nothing
in the doc that explicitely forbids it AFAICT but it says that you have
to be careful with sharing. But it could be a bug.
You can do it with a manager, however, but this involves an additional
process under the hood.
if __name__ == "__main__":
manager = multiprocessing.Manager()
lock = manager.Lock()
pool = multiprocessing.Pool(processes=5)
for i in xrange(100):
pool.apply_async(func=RunFunc, args=(i,lock))
pool.close()
pool.join()
--
Piet van Oostrum <piet at cs.uu.nl>
URL: http://pietvanoostrum.com [PGP 8DAE142BE17999C4]
Private email: piet at vanoostrum.org
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