Also this script will run on a machine with 2 cpus. Will the threading enable it to use both cpu's?

Perhaps, this will depend on various things. It'll depend on the threading implementation on the OS that's being used, but it will also depend on the sceduling policy of your OS. If for instance your database is running on the same machine, its process might use enough CPU time to occupy a CPU by its own.

Threads may be an answer if you can split your CPU bounded tasks into two - you only have one CPU bound task (the actual parsing), but that can easily be split into two - have each thread deal with half a file. However, instead of using two threads, it's much easier to use two processes (depending on your OS, you might even get more CPU time slots that way), and you save the not insignificant overhead Perl threads will give you. Now you might want to use separate threads to do your I/O as well. But that is something you should only consider if it's an actual bottleneck - and if it is, you can use separate processes as well, and have them communicate with pipes.

Abigail