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Re: Problem with multiprocessing module from Python
- From: Christopher Faylor <cgf-use-the-mailinglist-please at cygwin dot com>
- To: cygwin at cygwin dot com
- Date: Thu, 31 Oct 2013 23:05:53 -0400
- Subject: Re: Problem with multiprocessing module from Python
- Authentication-results: sourceware.org; auth=none
- References: <CAHhGz88t8H_xQ6h-a6-aQrMf+wTOVT6gMnx42tMpjs=3=qGVTQ at mail dot gmail dot com> <l4ei86$cos$2 at ger dot gmane dot org> <l4p2uq$ps8$1 at ger dot gmane dot org> <l4p6h3$801$1 at ger dot gmane dot org> <20131029205935 dot GC392 at ednor dot casa dot cgf dot cx> <l4p8oi$24u$1 at ger dot gmane dot org> <l4p8vj$24u$3 at ger dot gmane dot org> <20131030093313 dot GA28558 at calimero dot vinschen dot de> <l4u7er$2vj$1 at ger dot gmane dot org> <20131031184114 dot GD6599 at ednor dot casa dot cgf dot cx>
- Reply-to: cygwin at cygwin dot com
On Thu, Oct 31, 2013 at 02:41:14PM -0400, Christopher Faylor wrote:
>On Thu, Oct 31, 2013 at 06:27:39PM +0000, Jean-Pierre Flori wrote:
>>Le Wed, 30 Oct 2013 10:33:13 +0100, Corinna Vinschen a ??crit??:
>>
>>> On Oct 29 21:22, Jean-Pierre Flori wrote:
>>>> Le Tue, 29 Oct 2013 21:19:14 +0000, Jean-Pierre Flori a ??crit??:
>>>>
>>>> > Le Tue, 29 Oct 2013 16:59:35 -0400, Christopher Faylor a ??crit??:
>>>> >> If you want this fixed, the easiest way to get that to happen is to
>>>> >> post a simple test case which reproduces the problem. That is not
>>>> >> the code snippet that you sent. A real working example would be
>>>> >> required.
>>>> > Sorry about that.
>>>> >
>>>> > Here you go:
>>>> > """
>>>> > from multiprocessing import Pool
>>>> >
>>>> > def f(x): return x
>>>> >
>>>> > p = pool(2)
>>>> >
>>>> > p.map(f, [1, 2])
>>>> > """
>>>> And I managed to introduce a typo. The third line should read Pool, so
>>>> it is:
>>>> """
>>>> from multiprocessing import Pool
>>>>
>>>> def f(x): return x
>>>>
>>>> p = Pool(2)
>>>>
>>>> p.map(f, [1, 2])
>>>> """
>>>
>>> Works for me. I guess. At least, if I run the script, nothing happens:
>>>
>>> $ python x.py $
>>>
>>> Same on 32 and 64 bit Cygwin.
>>>
>>>
>>> Corinna
>>
>>I think I got to the bottom of this.
>>It seems the new implem of sem_getvalue in cgwin1.dll is the cause, see:
>>http://cygwin.com/ml/cygwin-patches/2013-q3/msg00006.html
>>It may also explain the random reproducibility if sval stays uninitialized
>>or something like that (I did not check it is the case though).
>
>I doubt that was the problem. More likely it is something related to
>the changes in thread.cc that followed that change.
Actually I misread the CVS log. It's more likely that this is due to changes
that happened just prior to the above change.
cgf
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