You really should have a look at Apache::Cache, too! It's doing exactly what you described.. The bad news is, that it doesn't come with the standard package and is likely to not be installed on the machine you want to have it run on.

A more general approach would be using Apache::Storage, which isn't included by default either :( Both of the above modules provide inter-process shared memory, btw.

If you really do want to do it yourself, I would at least look how this modules are doing their job; you probably can learn a lot by doing this.. Especially using shared memory is something you really do want to have..

Regards,
-octo