I am running the following on a Dell R610 (Quad core & 12GB RAM): Red Hat Enterprise Linux Server release 5.5 httpd 2.2.3 PHP 5.1.6
The web application running on this server is randomly leaking memory. Since the application is fairly big I have spent today trying to come up with a way to profile or trace the culprit script. The best tool I have so far is strace using strace -p PID -tt -o trace4.log -s 256. Unfortunately the memory usage can jump from 20m to 791m in a matter of seconds so running strace on the culprit process does not yield anything useful.
I tried starting httpd using strace strace -f -o trace_all.log /etc/init.d/httpd start, but unfortunately this causes extreme lag and unresponsiveness since the site receives fairly high traffic.
I understand that it is not best practice to debug in the production environment, but I am trying to narrow down what page and/or script is causing this issue and have been unable to replicate the problem when testing in the development environment
Any suggestions would be greatly appreciated.
Another, less intrusive way, to get an idea of where the memory is going is to run pmap. Running pmap -x will dump out a list of all the memory allocated to the process. It's broken down by memory address and includes size of the allocation, whether the memory is private to this process or shared, and a mapping as to what is being used by that memory (shared library/stack).