[pygtk] Help: Problems with threads and pygtk

N. French nbm_clan at yahoo.com
Fri Oct 6 01:16:06 WST 2006

Did you surround any accesses to GTK objects with the below calls?

gtk.threads_enter() # can't touch a GTK object w/o a thread lock

Without this bad stuff will happen.  I admit I don't fully understand
why this is needed but I found it either on the FAQ or someone
suggested it here.

--- David Hirschfield <davidh at ilm.com> wrote:

> I've run into a serious problem using threads with pygtk, and I was 
> hoping someone could give me suggestions.
> My program is a pygtk interface with a "processor" thread that pulls 
> from a safely synchronized queue of "requests" and processes each
> one.
> Seems simple, and it should have been...but it freezes solid when I
> run 
> it. Not a traceback of any kind, the interface and the python 
> interpreter freeze.
> I've checked all the things that should be obvious problems:
> I'm calling:
> gobject.threads_init()
> gtk.gdk.threads_init()
> before gtk.main() is called
> There is no race condition or blocking call causing everything to get
> stuck.
> The thread's only interaction with the rest of the program is via the
> Queue.Queue object that keeps the requests to be processed.
> I've stepped through with pdb and it freezes in a completely
> innocuous 
> place in the code (during a loop where I append to a list).
> The freeze occurs in slightly different places depending on what kind
> of 
> debugging code I put in, changes to the order of things, etc...so it 
> feels like it's some kind of corruption in the interpreter stack.
> Running the processor thread in a dummy app without the pygtk part
> never 
> freezes up.
> Running the pygtk app with a non-threaded processor, which just 
> sequentially runs the requests and waits till they complete, never 
> freezes up.
> I'm at my wit's end here...I know threads are just asking for
> trouble, 
> and usually I avoid them, but circumstances here basically require 
> threading (all the request time is spent waiting on different kinds
> of 
> IO). The setup was so simple, I figured I couldn't possibly run into 
> trouble...yet here I am.
> So, anyone have any idea what could cause the entire python
> interpreter 
> to freeze solid? Are there known issues with pygtk and python threads
> that I should be aware of? Is there some way to verify that the 
> interpreter stack is not getting screwed up somehow?
> Any help at this point would really be useful,
> -Dave
> -- 
> Presenting:
> mediocre nebula.
> _______________________________________________
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> Read the PyGTK FAQ: http://www.async.com.br/faq/pygtk/

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