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Enable Core Dumping

Got an intermittent crash with Apache? If the server is Seg Faulting, you can try the following :-

Note – this worked for us using a Centos 5 Server with Apache 2.

Read Apache's advice on crashing here: http://httpd.apache.org/dev/debugging.html#crashes

Edit the hosts.conf file to enable core dumping

This could be the file /etc/httpd/zzzz_YOUR_CUSTOM_CONFIG.conf (our Apache appended custom config)

1. Add the following lines (ours are in permanently commented)

# enable core dumps
CoreDumpDirectory /var/tmp
# enable rewrite logging
RewriteLog "/var/log/httpd/rewrite_log"
# set rewrite log level
RewriteLogLevel 3

This also enables Rewrite logging so if your problem is related to modrewrite, you've got a chance to pinpoint it.

2. Next, enable core dumps by removing any restrictions placed on them by the kernel like so in your server console:

ulimit -c unlimited

3. Restart Apache

service httpd restart

That's it! Remember not to leave it on for too long as Core dumps can be very big! Also, mod rewrite logging is a resource hog.

To undo –

1. reset the resource restrictions on your server console:

ulimit -c 0

2. Comment the same three lines in the Apache conf file.

3. Restart Apache

service httpd restart

Happy debugging! 😉

Jamie

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