Perl in a Nutshell, 2nd Edition

Chapter 11. Web Server Programming 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 repeatedly spawning CGI scripts 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 slow to a crawl.

The solution to this problem is mod_perl. mod_perl, written by Doug MacEachern and distributed under CPAN, embeds the Perl interpreter directly into the web server. The effect is that your CGI scripts are precompiled by the server and executed without forking, thus running much more quickly and efficiently. Furthermore, CGI efficiency is only one facet of mod_perl. Since mod_perl is a complete Apache/Perl hybrid, other benefits to mod_perl include:

• Writing server-side includes in Perl

• Embedding Perl code into the Apache configuration files

• Writing complete Apache modules in Perl