Why does my script use so much more memory when run with mod_perl?
memory-management, mod-perl, perl
Solution
I guess when you run your script under mod_perl, you get your script's memory usage, plus mod_perl's, plus apache's.
See also the answers to these questions:
- How can I programmatically determine my Perl program’s memory usage under Windows?
- Perl memory usage profiling and leak detection?
Problem
I'm trying to learn how to profile perl memory. I have a very simple Perl hello-world script and I want to know its size in memory. I use GTop utility to measure the memory (recommended in mod_perl book by Stas Beckman). GTop provides the results that confuse me. When I run the script from the command line GTop says: 7M. When I run it under `mod_perl`, GTop says: 54M. Why so much?! Why script memory grows so much under `mod_perl`? Or maybe I measure the memory in a wrong way? How do you profile perl script memory? Here are the script and its output (I have added commas manually to easily read the numbers) Run from command-line ``` > perl simple.pl size: 7,282688 share: 2,027520 diff: 5,255168 ``` Run under mod_perl ``` size: 54,878208 share: 4,661248 diff: 50,216960 ``` Script simple.pl ``` #!/usr/bin/perl use strict; use warnings; use CGI (); my $cgi = CGI->new; print $cgi->header('text/plain'); use GTop; print "Hello, world!\n"; my $m = GTop->new->proc_mem($$); print "size: ".$m->size."\n"; print "share: ".$m->share."\n"; my $diff = $m->size - $m->share; print "diff: $diff\n"; ```