You may be interested in Data::GUID for generating your unique process ID.

If your processing code runs on a single system you can use PIDs to uniquely identify currently running processes. If you are running across a number of systems use a GUID to identify a task and map that to a system name and PID to allow monitoring task progress. This stuff is commonly enough done that much of it is likely already provided in a module, but my quick CPAN search didn't turn up anything promising.