Python 2.6, multiprocessing module and BSD

[Jesse Noller]

On Wed, Oct 22, 2008 at 10:31 AM,  <YouCanCallMeAl at gmail.com> wrote:
> 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
> --
> http://mail.python.org/mailman/listinfo/python-list
>

I know I really appreciate the additional set of eyes on this, so thanks Alan!