Re: Problem with multiprocessing module from Python

[Christopher Faylor <cgf-use-the-mailinglist-please at cygwin dot com>]

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.

cgf

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