Gtk (and specifically matplotlib) support in ipython

Community matplotlib-users
1

Hi all,

after help and discussions with John, I'm putting up AS ALPHA CODE, a small script which will load ipython in a multithreaded mode which allows it to run GTK gui apps, and in particular matplotlib with the GTK backends.

Please note that using this requires at the moment _both_ CVS ipython and CVS matplotlib, since John and I have worked in conjunction to make the necessary changes.

The code already works fairly well, with one significant caveat: any process started via os.system() (whether directly or implicitly using !cmd) will hang after a while. I have currently no solution for this, but will welcome any ideas. Note that the problem seems to only affect long-running GUI apps, simple '!grep foo *' type things appear to function just fine. But something like '!gv foo.eps &' will open gv, and after about 30 seconds the gv instance stops responding to all keyboard/mouse input.

Debugging multithreaded code is _very_ tricky, but this tool may prove useful to many who want the interactive convenience of ipython combined with the better matplotlib backends, or other GTK apps. All feedback from willing testers will be very welcome.

Note that those wanting to use matplotlib interactively, and willng to stick to the Tk backends, can already do so. Tk does not require manual threading control, so it works perfectly OK with normal ipython. John already posted in the past a 'pylab' ipython profile which loads and configures matplotlib for such use, I can repost it if necessary.

This will become part of ipython 0.6.3, but I want to try to resolve the os.system() deadlock first. Since both John and I are complete ignoramuses on threading issues, help from anyone with knowledge on the topic is most welcome.

If you don't want to update to CVS ipython/matplotlib but think you may have an idea, you can use this small shell for tests:

http://amath.colorado.edu/faculty/fperez/tmp/pyint-gtk.py

It provides a basic multithreaded shell as a standalone python script (no matplotlib or ipython needed), and will show the os.system() deadlock problem.

Many thanks in advance for any feedback, and to John for all the help on this. We (I assume I speak for both John and I here :slight_smile: hope you all find it useful.

Best,

f

ipython-gtk (5.34 KB)

2

The code already works fairly well, with one significant

    > caveat: any process started via os.system() (whether directly
    > or implicitly using !cmd) will hang after a while. I have
    > currently no solution for this, but will welcome any ideas.
    > Note that the problem seems to only affect long-running GUI
    > apps, simple '!grep foo *' type things appear to function just
    > fine. But something like '!gv foo.eps &' will open gv, and
    > after about 30 seconds the gv instance stops responding to all
    > keyboard/mouse input.

You probably already have tried this but how about using
os.spawnl(...). Here a simple use case:

pid = os.spawnl(os.P_NOWAIT, script, script)

cheers,
prabhu