I've run into a situation where data was coming in real time
and couldn't be ignored, but also needed to be displayed
and stored in database.

Writing and reading a file constantly was too "messy" in
terms of possible conflicts from two different programs -
even with lockfiles.

Perls Interprocess Communication (IPC) solved the problem.

See:

http://www.perldoc.com/perl5.6/pod/perlipc.html

CPAN also many variations in IPC (222 hits on "IPC" alone).