From ehs at pobox.com  Mon May  2 15:05:22 2011
From: ehs at pobox.com (Ed Summers)
Date: Mon, 2 May 2011 09:05:22 -0400
Subject: [Web-SIG] wsgi + multiprocessing
Message-ID: <BANLkTinMWzoj_RS5aSBHY-9NN3HJn7Fzmw@mail.gmail.com>

I realize this is probably a pretty silly question, but I was
wondering if anyone can provide any insight.

I've been trying to use the multiprocessing [1] in a WSGI environment
and have observed what appears to be deadlock behavior under
mod_wsgi+django and
web.py. I created a minimal example web.py to demonstrate [2]. If you
have web.py available you should be able to run that script and then
point your browser at:

    http://localhost:8080/

and then watch your browser hang when you visit:

    http://locahost:8080/?multiprocessing=1

Going forward I'm most likely going to move this functionality to an
asynchronous queue (celery, etc) but I was wondering if
multiprocessing + WSGI was generally known to be something to avoid,
or if it was even forbidden somehow.

Any assistance you can provide would be welcome.

//Ed

[1] http://docs.python.org/library/multiprocessing.html
[2] https://gist.github.com/951570

From ehs at pobox.com  Mon May  2 15:30:24 2011
From: ehs at pobox.com (Ed Summers)
Date: Mon, 2 May 2011 09:30:24 -0400
Subject: [Web-SIG] wsgi + multiprocessing
In-Reply-To: <BANLkTinMWzoj_RS5aSBHY-9NN3HJn7Fzmw@mail.gmail.com>
References: <BANLkTinMWzoj_RS5aSBHY-9NN3HJn7Fzmw@mail.gmail.com>
Message-ID: <BANLkTinCXBukoUE7fpVAR-gcHVNhjd-OcA@mail.gmail.com>

Actually this appears to only be a problem for Django and web.py when
they are running under mod_wsgi. I don't see the hanging behavior when
running under django runserver, or single threaded web.py ... so
perhaps this question is best asked over on the mod_wsgi discussion
list?

//Ed

On Mon, May 2, 2011 at 9:05 AM, Ed Summers <ehs at pobox.com> wrote:
> I realize this is probably a pretty silly question, but I was
> wondering if anyone can provide any insight.
>
> I've been trying to use the multiprocessing [1] in a WSGI environment
> and have observed what appears to be deadlock behavior under
> mod_wsgi+django and
> web.py. I created a minimal example web.py to demonstrate [2]. If you
> have web.py available you should be able to run that script and then
> point your browser at:
>
> ? ?http://localhost:8080/
>
> and then watch your browser hang when you visit:
>
> ? ?http://locahost:8080/?multiprocessing=1
>
> Going forward I'm most likely going to move this functionality to an
> asynchronous queue (celery, etc) but I was wondering if
> multiprocessing + WSGI was generally known to be something to avoid,
> or if it was even forbidden somehow.
>
> Any assistance you can provide would be welcome.
>
> //Ed
>
> [1] http://docs.python.org/library/multiprocessing.html
> [2] https://gist.github.com/951570
>

From dholth at gmail.com  Mon May  2 19:01:11 2011
From: dholth at gmail.com (Daniel Holth)
Date: Mon, 2 May 2011 10:01:11 -0700 (PDT)
Subject: [Web-SIG] wsgi + multiprocessing
In-Reply-To: <BANLkTinCXBukoUE7fpVAR-gcHVNhjd-OcA@mail.gmail.com>
Message-ID: <25022616.736.1304355671481.JavaMail.geo-discussion-forums@yqkv17>

http://www.doughellmann.com/PyMOTW/multiprocessing/basics.html#daemon-processes 
?
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.python.org/pipermail/web-sig/attachments/20110502/76826e74/attachment.html>