The forks.pm module is a drop-in replacement for threads.pm.  It
has the same syntax as the threads.pm module (it even takes over
its namespace) but has some significant differences:

- you do _not_ need a special (threaded) version of Perl
- it is _much_ more economic with memory usage on OS's that support COW
- it is more efficient in the startup of threads
- it is slightly less efficient in the stopping of threads
- it is less efficient in inter-thread communication

If for nothing else, it allows you to use the Perl threading model
in non-threaded Perl builds and in older versions of Perl (5.6.0
and higher are supported).