Re: Debugging for mod_perl

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On Fri, 17 Dec 2004 07:59:19 -0500
Sean Davis <sdavis2@xxxx.xxx.xxx> wrote:

> I am a new user to mod_perl.  I have a module that does some 
> computation and has methods for generating png (using GD) and html.  I
> 
> wrapped it in a thin content handler.  It works as expected except
> that when I include it in the httpd.conf file, I start noticing that
> the png colors are altered on some requests.  Furthermore, it also
> alters the colors on another script (running under apache::registry)
> that generate pngs dynamically.  However, when I run the same second
> script under plain cgi and under apache::registry without my handler
> included in httpd.conf, it does not have these display the strange
> color behavior.  Running my calculation module with warnings and use
> strict results in no warnings, etc.
> 
> I know I haven't given enough information to solve the problem, but I 
> feel like I have some issue with a global variable or a memory leak 
> somewhere that is causing a problem in the mod_perl setting.  
> Unfortunately, I am using multiple third-party modules, also, so 
> tracking this down by hand is a difficult proposition at best.  What 
> tools/steps would folks suggest that I use to track down the issue?

  You might check out Apache::DB from cpan, it will give you a Perl
  debugger (much like gdb) so you can step through your code, and
  the third-party modules code (if in Perl) and see where things are
  going wrong.  

  You might also try running your httpd with only one process ( -X
  I believe ) and see if it has the same behavior.  I would also
  check out: 

 
http://perl.apache.org/docs/1.0/guide/porting.html#Sometimes_it_Works__Sometimes_it_Doesn_t

  Hope this helps! 

 ---------------------------------
   Frank Wiles <frank@xxxxx.xxx>
   http://www.wiles.org
 ---------------------------------


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