The "forks" pragma allows a developer to use threads without having to 
have a threaded perl, or to even run 5.8.0 or higher. There were a number 
of goals that I am trying to reach with this implementation.

The standard Perl 5.8.0 threads implementation is very memory consuming, 
which makes it basically impossible to use in a production environment, 
particularly with mod_perl and Apache. Because of the use of the standard 
Unix fork() capabilities, most operating systems will be able to use the 
Copy-On-Write (COW) memory sharing capabilities (whereas with the standard 
Perl 5.8.0 threads implementation, this is thwarted by the Perl interpreter 
cloning process that is used to create threads). The memory savings have 
been confirmed.

You should be able to run threaded applications unchanged by simply making 
sure that the "forks" and "forks::shared" modules are loaded, 
e.g. by specifying them on the command line.

WWW:	http://search.cpan.org/dist/forks/