Webmaster in a Nutshell, Third Edition

Running CGI Scripts with mod_perl

A common criticism of CGI is that it requires forking extra processes each time a script is executed. If you have only a few hits an hour, or even a few hits a minute, this isn’t a big deal. But for a high-traffic site, lots of CGI scripts repeatedly spawning can have an unfortunate effect on the machine running the web server. The CGI scripts will be slow, the web server will be slow, and other processes on the machine will come to a crawl.

Withmod_perl and Apache::Registry, however, your CGI scripts are precompiled by the server and executed without forking, thus running much more quickly and efficiently.

The mod_perl installation enables the PerlHandler callback hook by default and by installing the Apache::Registry module. PerlHandler is the handler used for the content retrieval stage of the server transaction. Apache::Registry is the Perl module that emulates the CGI environment so you can use “standard” Perl CGI scripts with mod_perl without having to rewrite them (much). This is by far the cheapest way to get improved CGI performance.

With Apache::Registry, each individual CGI program is compiled and cached the first time it is called (or whenever it is changed) and remains available for all subsequent instances of that CGI script. This process avoids the costs of startup time.

Whereas most CGI scripts are kept in /cgi-bin/, scripts that use Apache::Registry are placed in a separate directory, e.g., /perl-bin/. The access.conf Apache ...