[Cheetahtemplate-discuss] Cheetah causing Python to segfault

[Warren S. <wa...@wa...>]

I have been evaluating Webware and Cheetah for possible use in a number
of upcoming applications.  For the most part, I like what I see.

As part of my evaluation, I have been developing a proof-of-concept
application and have run into a situation in which it seems that Cheetahis causing Python to segfault.

My platform looks like this:

OS: FreeBSD 4.6-RELEASE-p2
Web Server: Apache 1.3.26 with mod_webkit
Python: 2.2.1
Webware: 0.7
Cheetah: 0.9.13

I built the application in the manner recommended by the docs, using the
inheritance model.  In doing so, my inheritance tree became moderately
deep as I tried to extract common behavior into base classes, anticipating
being able to share these between several applications.
My inheritance tree looks like this:

SkeletonPage  # Included with Cheetah
  BaseLogic.py   # My global base class
    BaseTemplate  # My global base template
      SidebarTemplate  # My global "Sidebar" template
        AppBaseLogic  # My app's base class
          AppBaseTemplate  # My app's base template
            Page1Logic
              Page1
                Page4Logic
                  Page4
            Page2Logic
              Page2
            Page3
            etc...

Everthing worked fine untill I began work on Page4.  I found that if I
requested Page4 (or even Page4Logic) right after restarting WebKit, Python
would segfault.  This was surprising given that I had experienced
absolutelyno stability problems with Python or WebKit up to this point.

After much experimentation I found that one of the things that the crashes
seemed to have in common was the inheritance level of the servlet
requested.
Wanting to know if this was a problem produced by my code or by the
Webware and Cheetah code, I changed all of my modules, from BaseLogic
down, to:
from MODULE_NAME import BASE_CLASS_NAME
class SUB_CLASS_NAME(BASE_CLASS_NAME):
     pass

Still, any request for Page4Logic or below after restarting WebKit would
cause Python to segfault.
Wanting to know if the problem was with Webware or Cheetah, I changed
BaseLogic to inherit from WebKit.Page and the segfaults stopped.
From this I suspect that there may be a bug in the Cheetah code somewhere,
or that Cheetah is exposing a bug in Webware or Python 2.2.1 somehow. 
Since it only happens right after WebKit has been restarted, I suspectit might be code that only executes on import.

It seems I can work around this by requesting a higher level page before
Page4.  However, since I will not be able to control the sequence of real
requests, I cannot seriously consider using Cheetah for a real application
until I resolve this issue.
Thanks in advance for any help that anyone can give me.

-- 
Warren Smith
wa...@wa...