Python 2.6, multiprocessing module and BSD

[YouCanCallMeAl at gmail.com]

On Oct 22, 8:11 am, "Jesse Noller" <jnol... at gmail.com> wrote:
> On Tue, Oct 21, 2008 at 6:45 PM,  <YouCanCallM... at gmail.com> wrote:
> > It seems that the multiprocessing module in 2.6 is broken for *BSD;
> > I've seen issue 3770 regarding this. I'm curious if there are more
> > details on this issue since the posts in 3770 were a bit unclear. For
> > example, one post claimed that the problem was that sem_open isn't
> > implemented in *BSD, but it is available on FreeBSD 7 (I checked). I'd
> > be willing to help get this working if someone could point me in the
> > right direction.
> > --
> >http://mail.python.org/mailman/listinfo/python-list
>
> The BSD issue was raised late in the cycle for 2.6. The problem is
> that FBSD's support is "very experimental" as Phillip points out - and
> OpenBSD doesn't even have them.
>
> Due to the lateness of the issue and a finite amount of time I have to
> work on things, I chose to disable support for this on the various
> *BSDs until I can cook up a stable patch or have one provided by
> someone more familiar with the inner workings of Free-BSD. OpenBSD
> support is a non-starter.
>
> Ideally, I would like to get this fixed and put on the 2.6 maint
> branch ASAP, but I haven't had a chance to circle back to it.
>
> Also note Nick's comment in that bug: "Unfortunately, our OpenBSD and
> FreeBSD buildbots are so unreliable that they don't get much attention
> when they go red"
>
> Stable reliable buildbots and a few more volunteers more familiar with
> BSDs might be a great and welcome addition to python-dev.
>
> As for getting this working - I would love a patch. You are going to
> want to start with python-trunk and look in setup.py. You are going to
> want to adjust the flags the package uses:
>
>         elif platform in ('freebsd5', 'freebsd6', 'freebsd7', 'freebsd8'):
>             # FreeBSD's P1003.1b semaphore support is very experimental
>             # and has many known problems. (as of June 2008)
>             macros = dict(                  # FreeBSD
>                 HAVE_SEM_OPEN=0,
>                 HAVE_SEM_TIMEDWAIT=0,
>                 HAVE_FD_TRANSFER=1,
>                 )
>             libraries = []
>
> You will also need to look at: Lib/multiprocessing/synchronize.py to
> disable the import error - Modules/_multiprocessing/multiprocessing.h
> will need to be updated for the proper ifdefs for the bsd(s) as well.
> Finally, the core of the semaphore usage is in
> Modules/_multiprocessing/semaphore.c
>
> I apologize we/I could not get this in for 2.6
>
> -jesse

This is exactly the sort of response I was hoping for. Thanks for the
additional background on the problem. I'll take a look at the code and
see if I can figure out a patch. I'll also read up on the buildbot
issue ( I think I saw a link about that)...I might have a stable co-
located FreeBSD box that could be used.
-Alan