Le Thu, 31 Oct 2013 14:41:14 -0400, Christopher Faylor a écrit : > 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
I must admit that was just a guess. The thread.cc code changed whereas python code in Modules/ _multiprocessing/semaphore.c did not. The python multiprocessing module (file semaphore.c) contains: """ if (sem_getvalue(self->handle, &sval) < 0) { return PyErr_SetFromErrno(PyExc_OSError); } else if (sval >= self->maxvalue) { PyErr_SetString(PyExc_ValueError, "semaphore or lock " "released too many times"); return NULL; } """ Changing this to """ sval = sem_getvalue(self->handle, &sval); if (sem_getvalue(self->handle, &sval) < 0) { return PyErr_SetFromErrno(PyExc_OSError); } else if (sval >= self->maxvalue) { PyErr_SetString(PyExc_ValueError, "semaphore or lock " "released too many times"); return NULL; } """ to emulate the previous behavior of sem_getvalue seems to solve my problem (and was easier than rebuilding cygwin1.dll). Commit http://cygwin.com/cgi-bin/cvsweb.cgi/src/winsup/cygwin/thread.cc? rev=1.286&content-type=text/x-cvsweb-markup&cvsroot=src would be exactly what I need. I'll just be waiting for 1.7.26. Hopefully this will get sorted out. Best, JP -- Problem reports: http://cygwin.com/problems.html FAQ: http://cygwin.com/faq/ Documentation: http://cygwin.com/docs.html Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple