strange issue w/ script "hanging"

geektron has asked for the wisdom of the Perl Monks concerning the following question:

one of the older CGI::Application-based pieces here has started exhibiting some strange behaviour. one link (well, one submit into one run_mode) just hangs. the wheels spin, but nothing spits out into the error_log, nothing to the screen ... nothing.

i've added warn "this is the end of sub setup() "; where you would expect a comment like that. even added a warning in the calling script to see where the problem is.

thing is, about ... 2+ minutes after the button is pressed I'll see:

Premature end of script headers: Financial.cgi, referer: <myscript>/cg
+i-bin/Financial.cgi?cgitoken=&rm=pulluprecord&args=3274
[download]

then nothing for a while again ... then another few minutes (literally minutes) some of the warnings i added to the called runmode get spat out. i've even resorted to a warning just after the usual my $self = shift; line .. and even that doesn't show up in the error log in a timely fashion.

all the other page links work ... i've already revamped the code slightly to use just a hash in sub setup() rather than the subrefs that older versions use ...

so i'm not even sure where to start looking. this is a strange one. anyone have another pointer or three for me?

Comment on strange issue w/ script "hanging" Select or Download Code

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Re: strange issue w/ script "hanging" by Fletch (Bishop) on Feb 10, 2005 at 01:23 UTC
If this is being run by Apache try and run it (`httpd`) with the `-X` flag which doesn't fork off any children (the one process handles a single request). If that still hangs, try running `httpd -X` under whatever your OS' system call tracing facility is (`strace`, `ktrace/kdump`, or `truss`; be sure to tell it to follow across forks) and see if that gives any insight into where it's hanging and what it's trying to accomplish underneath. Or perhaps change your `#!` line to use Devel::Trace and see if that dumps anything enlightening into your error log.	[reply]
Re: strange issue w/ script "hanging" by cowboy (Friar) on Feb 10, 2005 at 07:16 UTC
A million questions could be asked, to try to figure out what's going wrong with your script. Is there a database? Are you reading from a file? Are you reading from a socket? Is the script doing anything 'weird'? Ect ect Would you mind posting some code to help us out?	[reply]
Re: strange issue w/ script "hanging" by aufflick (Deacon) on Feb 10, 2005 at 06:49 UTC
If it's a stand-alone cgi you can run it on the command line or with the perl debugger and step through it until you find where it hangs (see `perldoc perldebug`). If you are running inside mod_perl you can still use the debugger quite simple - take a look at Apache::DB	[reply]