[pygtk] Strange crash issue on Windows w/ PyGTK, Cairo...

[CJ Kucera]

Hello list!

This is actually basically a repost of a message I sent over to the
Python list.  I've been suspecting that the problem is somewhere in
PyGTK or PyCairo, and I received one response over there which echoed
that sentiment, so here it is here.  Bear with me, this'll probably
be a long explanation...

I've been building an app which is meant to be run on both Linux and
Windows.  It uses PyGTK for its GUI, and the main area of the app is
a gtk.DrawingArea which I draw on using PyCairo.  I've been developing
on Linux, and it works great on that platform, with no issues that
I'm aware of.  When running on Windows, though, the app exhibits the
following behavior:

  1) When the .py of the main file which runs the application GUI first
  gets compiled to a .pyc (ie: the first time it's run, or the first
  time after .py modification), the application runs totally fine, with
  no apparent problems.

  2) Any attempt AFTER that, the application will start up, *start* to
  do its data-loading, but then almost immediately crash with an
  enigmatic "python.exe has generated errors and will be closed by
  Windows."  When it does so, there is no output whatsoever to the
  console that the application was launched from, and the crash doesn't
  always happen in exactly the same place.

The pattern remains the same, though - if the .pyc needs to be compiled,
the application works fine, but if not: boom.

I've been steadily stripping the program down to what I hoped would be a
small, reproducible app that I could post here, and I do intend to do so
still, but it's rather slow going.  For now, I was hoping to see if
anyone's ever heard of behavior like this before, and might know what
to do about it, or at least a possible avenue of attack.

As I've been reducing the program down, I've encountered even stranger
(IMO) behavior...  In one instance, changing a function name seemed to
make the program work.  I took out the handler which draws my app's
"About" box, and suddenly my problem went away.  Occasionally I would
remove a function and the app would suddenly *always* fail with that
Windows crash error, and I'd have to put the function back in.  Keep
in mind, these are functions which *aren't being called anywhere.*

Sometimes I could replace a function's entire contents with just "pass"
and the app would suddenly behave properly, or not behave at all.  More
recently, I've noticed that I can change the crash behavior just by
putting occasional "pass" statements in functions.  (ie: one 'pass' may
have no effect, putting two in may cause the app to always crash, etc).

It's almost as if whatever's doing the byte-compilation is getting
screwed up somehow, and really small changes to parts of the file which
aren't even being touched are having a huge impact on the application as
a whole.  It's seriously vexing, and certainly the oddest problems I've
seen in Python.

Windows versions I can reproduce this on: XP and win2k
Python versions I've reproduced this on:
  Python 2.5.4 with:
    PyGTK 2.12.1-2-win32-py2.5
    PyGObject 2.14.1-1.win32-py2.5
    PyCairo 1.4.12-1.win32-py2.5
  Python 2.6.1 with:
    PyGTK 2.12.1-3-win32-py2.6 
    PyGObject 2.14.2-2.win32-py2.6
    PyCairo 1.4.12-2.win32-py2.6
GTK versions used:
  gtk+ 2.12.9-win32-2 from the gladewin32 project
  gtk+-bundle 2.16.0-20090317_win32, from the other link on pygtk's
  download page

The 2.6 Python stuff I've actually only tried on win2k so far, not XP,
though given my history with this, I suspect that that wouldn't make a
difference.

Anyway, I'll continue trying to pare this app down to one manageable
script which I can post here, but until then I'd be happy to hear ideas
from anyone else about this.

Thanks!

-CJ