Re: [Cheetahtemplate-discuss] Cheetah causing Python to segfault
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Re: [Cheetahtemplate-discuss] Cheetah causing Python to segfault
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From: Warren S. <wa...@wa...> - 2002-07-18 16:15:17
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Here's some additional info.
With BaseLogic inheriting from SkeletonPage, If I change all of my
templates to
#from MODULE_NAME import BASE_CLASS_NAME
#extends BASE_CLASS_NAME
I get the segfault at Page4, but only after a restart.
If I change BaseLogic to inherit form WebKit.Page, I get exceptions from
the generated .py files since they expect to subclass Template.
If I strip the generated .py files down to
from MODULE_NAME import BASE_CLASS_NAME
class SUB_CLASS_NAME(BASE_CLASS_NAME):
pass
then the exceptions go away and I don't get segfaults anywhere.
If I change BaseLogic back to inheriting from SkeletonPage, but leave the
generated .py files in their stripped down state, I get segfaults on
EVERY page after a restart.
When I had been in this state previously, I hadn't checked any other
page but Page4, so I didn't realize that EVERY page was causing segfaults.
I suppose that since I am doing nothing more than sub-classing several
levels deep from SkeletonPage at this point, it may not have been intended
to be used this way.
Warren Smith said:
> Tavis Rudd said:
>> Hi Warren,
>> from your description it sounds like the problem might be related to
>> the import mechanisms Webware uses to load a servlet, though I'm not
>> sure why at this stage. I have a few questions:
>>
>> 1- have all of your .tmpl templates been converted to .py modules? I
>> assume yes.
>
> Yes.
>
>> 2- Do all of your direcories have an __init__.py file in them?
>
> I have an __init__.py in the directory that my context is pointing to.
> There are no __init__.py files in my app's "lib" directory or in my
> global "lib" directory.
>
>> 3- Does Python leave a core file befind?
>
> Yes it does.
>
>>
>> Tavis
>>
>> On July 17, 2002 02:00 pm, Warren Smith wrote:
>>> 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.
>>
>>
>>
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>
>
> --
> Warren Smith
> wa...@wa...
>
>
>
>
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--
Warren Smith
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