SPUG: Segmentation Fault in mod_perl
John Cokos, CEO, iWeb, Inc.
jcokos at iwebsys.com
Thu Mar 15 14:41:27 CST 2001
Basically the same system as you're running:
Latest versions of apache, php, and mod_perl, on RedHat 7.
I've seen this happen on Solaris boxes as well.
Not sure what the cause is, but you can find lots
of discussions about it on both the mod_perl email
lists, and the php email lists.
It's a known thingie.
========================================
John Cokos, President / CEO: iWeb Inc.
http://www.iwebsys.com
jcokos at ccs.net
========================================
----- Original Message -----
From: "Stephen Nickels" <snickels at u.washington.edu>
To: "John Cokos, CEO, iWeb, Inc." <jcokos at iwebsys.com>
Cc: "Richard Anderson" <Richard.Anderson at raycosoft.com>; "Jonathan Gardner" <gardner at sounddomain.com>; <spug-list at pm.org>; "Colin
Meyer" <cmeyer at helvella.org>
Sent: Thursday, March 15, 2001 11:42 AM
Subject: Re: SPUG: Segmentation Fault in mod_perl
> Wow, I've never seen this before. What versions are being run when you see
> this problem? I spent a summer with a bunch of boxes running mod_perl and
> php on apache, and never saw a problem. My home box runs linux 2.4.2,
> apache 1.3.12, php 4.0.1pl2 and mod_perl 1.24 and I've never had a
> mod_perl problem connecting to a database.
> I'm curious to know where and how you get these problems so I can watch
> for them in the future....
>
> --Steve
>
>
> On Thu, 15 Mar 2001, John Cokos, CEO, iWeb, Inc. wrote:
>
> > Although I'm not sure if this is related to the original
> > problem, it's food for thought, nonetheless .....
> >
> > I've noticed a quite serious problem when you have
> > php and mod_perl both compiled into apache. The problems
> > only arise when a mod_perl program attempts to
> > connect to a database. At that point, mod_perl programs
> > start throwing up Segfaults, and php scripts start returning
> > no data at all.
> >
> > Definitely a bug somewhere, where these 2 technologies
> > are bumping into each other's shared memory or something.
> >
> > I've found that in every case, turning php "off" always fixes
> > the mod_perl problem. While not the best solution, it
> > is the only solution when you're trying to do both.
> >
> > J-
> >
> > ========================================
> > John Cokos, President / CEO: iWeb Inc.
> > http://www.iwebsys.com
> > jcokos at ccs.net
> > ========================================
> > ----- Original Message -----
> > From: "Richard Anderson" <Richard.Anderson at raycosoft.com>
> > To: "John Cokos" <jcokos at iwebsys.com>; "Jonathan Gardner" <gardner at sounddomain.com>; <spug-list at pm.org>
> > Cc: "Colin Meyer" <cmeyer at helvella.org>
> > Sent: Tuesday, May 15, 2001 9:14 AM
> > Subject: Re: SPUG: Segmentation Fault in mod_perl
> >
> >
> > > I've done a bit of work on search engines, and I have a couple of thoughts:
> > >
> > > John pointed us toward a few potentential minor syntax problems. The out-of-memory problem will pop up quite a bit if you are
> > searching a large internap site like yahoo, yellowpages.com etc. and the search returns a lot of results. Imagine seaching the
NYC
> > phonebook for the string Smith!
> > >
> > > One try might be to use a more memory-efficient XML parser routine. Damian is probably a good resource on this (are you out
> > there, mate?).
> > >
> > > Another approach is to limit your search to returning the first 50 results you find. If the user wants more results, add a
link
> > at the top and bottom of the page that takes him to results 51-100, and so on
> > >
> > > In future versions, you might consider ranking the results based on some goodness-of-fit criterion based on the search string.
> > Word stemming and language dependencies are some more goodies to add.
> > > Richard Anderson, Ph.D. www.unixscripts.com
> > > Perl / Oracle / Unix Richard.Anderson at raycosoft.com
> > > Raycosoft, LLC Seattle, WA, USA
> > > ----- Original Message -----
> > > From: "John Cokos" <jcokos at iwebsys.com>
> > > To: "Jonathan Gardner" <gardner at sounddomain.com>; <spug-list at pm.org>
> > > Sent: Monday, March 12, 2001 8:06 PM
> > > Subject: Re: SPUG: Segmentation Fault in mod_perl
> > >
> > >
> > > > You're barking right up my tree here .... I do CGI
> > > > work for a living, and work with mod_perl quite
> > > > a bit.
> > > >
> > > > That being said, let me ask you a few preliminary
> > > > questions:
> > > >
> > > > 1. The CGI Script that actually runs: is it mod_perl
> > > > compliant, in terms of exit status, "use strict" compatability,
> > > > etc?
> > > >
> > > > 2. How do you have httpd.conf setup to accept mod_perl
> > > > programs?
> > > >
> > > > 3. Sounds like you're going through a lot of machinations
> > > > to get XML output. Seems to me that a "from scratch"
> > > > solution, or one that's designed from the outset to
> > > > work within the confines of mod_perl would be better
> > > > suited than to try and shoehorn in something else.
> > > >
> > > > Generally, coredumps from mod_perl are the result of
> > > > "dirty" coding. A few variables out of place, or a bad
> > > > exit status can kill it pretty quickly.
> > > >
> > > > John
> > > >
> > > > ----- Original Message -----
> > > > From: Jonathan Gardner <gardner at sounddomain.com>
> > > > To: <spug-list at pm.org>
> > > > Sent: Monday, March 12, 2001 4:16 PM
> > > > Subject: SPUG: Segmentation Fault in mod_perl
> > > >
> > > >
> > > > > Okay, run while you still can!
> > > > >
> > > > > We're running mod_perl on Apache. I am working on a module to
> > > > > allow people to search our pages.
> > > > >
> > > > > I got ht://dig. This is a fine piece of software, and it works great. Ht://dig
> > > > > has a program that works as a CGI script, and using the configuration files and
> > > > > templates, you can configure almost anything you would like to.
> > > > >
> > > > > We want to really customize stuff, really really customize it. So I figured
> > > > > we'd trick htdig to output XML, and use XML parser to parse it out, and then
> > > > > take that and convert it into hashes and arrays and scalars we can use to fully
> > > > > customize everything in Perl.
> > > > >
> > > > > Okay, so I wrote a module that takes the search parameters and returns a hash
> > > > > with all the results stored inside. I wrote a test script that runs from the
> > > > > command line and everything works beautifully. I am so happy I beam for joy!
> > > > >
> > > > > I plug it into Apache mod_perl and I get the dreaded segmentation fault. Not
> > > > > just once, over and over again, almost every time I try to run it.
> > > > >
> > > > > The only hint I have is that perhaps it is an out-of-memory problem. This would
> > > > > make sense. I have the program that consumes a lot of memory (the search), and
> > > > > XML::Parser trying to pack everything into 'Tree' style. But it doesn't fail
> > > > > during that - it fails when I start working on the tree with a couple of subs,
> > > > > so if it WAS a memory problem shouldn't it fail during the XML parsing or
> > > > > during the searching? How do I check to see how much memory the command-line
> > > > > script uses?
> > > > >
> > > > > What do I do to find out the problem, short of putting a "warn"
> > > > > between every line of code? How do I use the core dump - if it is useful at
> > > > > all? What rotting nuggets of useful knowledge are lodged in the wisdom
> > > > > teeth of the gurus, and could they use the toothbrush of the transfer of
> > > > > knowledge to reveal those morsels to me? :-)
> > > > >
> > > > > --
> > > > > Jonathan Gardner
> > > > > gardner at sounddomain.com
> > > > > (425)820-2244 x123
> > > > >
> > > > >
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