[matplotlib-devel] GtkAgg Backend and Threads

[Dennis M. <djm...@gm...>]

We have an app that creates some background threads and is doing work at 
the same time it displays a pylab figure.  We noticed the worker threads 
stopped working while we're looking at the figure and then things start 
working again after we close it.

Turns out, from the faq [1], you can have background threads with GtkAgg 
if you call gobject.threads_init().

I changed my matplotlib/backends/backend_gtk.py to:

try:
     import gobject
     import gtk; gdk = gtk.gdk
     import pango
     gobject.threads_init()
except ImportError:
     raise ImportError("Gtk* backend requires pygtk to be installed.")

Sure enough, I can now have my worker threads continue in the background 
while we're watching the figure.  I'm not sure if this should be the 
default behavior or if there ought to be a way to customize the backend 
for individual usage.

A side note however:  We run the same app with a wxPython frontend 
sometimes.  In this mode, the backend is WxAgg.  The Wx backend does not 
have the same default behavior as the GTK backend.  Our worker threads 
continue to do work properly with this backend.  I tried PyQt with a 
small test app as well.  It appears only GTK blocked everything so I 
think perhaps this change should be applied.

-Dennis

[1] http://bit.ly/buQROp