Well you have to test for your system, but usually perl's flock will block, and you are right it's a problem as you might end up with too many processes! I prefer non-blocking handles and do the polling myself. 'perldoc -f fcntl' will tell you how to set up non-blocking flags.

flock: "it waits indefinitely until the lock is granted"

I don't know of an easy to do what you want without polling. From the looks of it though, your locks are really short lived, so it should not be a problem.

Update: s/should be/should not be/