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From "Dan Yamins" <dyam...@gmail.com>
Subject [users@httpd] Another "Premature end of script" headers problem
Date Wed, 19 Nov 2008 05:17:35 GMT
Sorry, I posted this in the middle of someone else's question before ... so
I'm posting it again in its own thread.  Hopefully someone has some ideas:

I'm running a python script using CGI on a local apache-served virtual host.
(It' just an internal development project.)   The project involves layout of
some large graph network structures, which are then viewed via a web-based
graph-vieweing tool.  The script uses the "Pygraphviz" module (
http://networkx.lanl.gov/pygraphviz/)  to generate .svg files with layouts
of the graph and the "zgrviewer" applet to view the graphs.    During the
script, I first construct the graph.  After using the pygraphviz module to
do the layout of the graph as a data structure in memory, I invoke the
pygraphviz method "draw", which saves the graph to an .svg on disk.  Then I
issue the HTML code invoking the zgrviewer applet, which uses the saved .svg
file.

Sometimes -- only _sometimes_ -- when the script invokes the "draw" method,
I get a "premature end of script headers" problem, with error code 500.
Because the .draw method is outputing a file to disk, it seems like it might
be a permissions-related problem. But I can't figure out what t is easily,
becuase the problem only happens occasionally.  Moreover, when it happens,
if I just hit "refresh" on the browser to run the script again, then it
usually runs fine.    I haven't been able to figure out more than this.

Any suggestions greatly appreciated!
Thanks,
Dan

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