[Python-Dev] Signals+Threads (PyGTK waking up 10x/sec).

[Guido van Rossum]

The OLPC project is also interested in getting this solved.

Can you explain how Gtk uses signals and threads together? The
combination strikes me as a recipe for disaster, but I'm probably
missing something.

--Guido

On Dec 6, 2007 8:56 PM, Sean Reifschneider <jafo-python-dev at tummy.com> wrote:
> Overview (my reading of it):
>
>    PyGTK wakes up 10x a second in it's main loop because signals may be
>    delivered to another thread and will only get picked up if the mainloop
>    wakes up.
>
> In the following thread:
>
>    http://mail.python.org/pipermail/python-dev/2006-September/068569.html
>
> it sounds like the patch at:
>
>    http://bugs.python.org/issue1564547
>
> doesn't solve the problem.  A recent gnome bug brings this issue back up:
>
>    http://bugzilla.gnome.org/show_bug.cgi?id=481569
>
> I went ahead and closed the python issue as "rejected" to hopefully get
> some more activity on it.
>
> I thought about this some, and I wondered if there was some way we could
> signal the sleeping thread when a signal came in on another thread.  Like
> perhaps we could make some code to create a pipe, and put it someplace that
> all threads could get access to.  Then, if a thread gets a signal, write on
> this pipe.  The mainloop could include this file descriptor in the set it's
> watching, so it would wake up when the signal came in.
>
> Is this something Python should provide, or something PyGTK should do?  If
> an approach like the above would work, we could make it so that select()
> always created this file descriptor and added it to one of the FD sets, so
> that it would do the right thing behind the scenes.
>
> I have no idea if this is a reasonable approach, but it's something that
> came to mind when I thought about the problem and was an approach I didn't
> see mentioned before in the discussion.
>
> Thanks,
> Sean
> --
>  I live my life like I type; Fast with lots of mistakes.
> Sean Reifschneider, Member of Technical Staff <jafo at tummy.com>
> tummy.com, ltd. - Linux Consulting since 1995: Ask me about High Availability
>       Back off man. I'm a scientist.   http://HackingSociety.org/
>
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-- 
--Guido van Rossum (home page: http://www.python.org/~guido/)