Are you sure you want to use system (which consists of a fork, an exec and a waitpid) instead of exec? If you need to return to the Perl script, great. If not, use exec. As far as I can tell, both will work.

Update: On second thought, you need to call finish, so exec is out. Looking at the module's guts, system should be ok, since the module doesn't care what the children do, as long as they call finish when they are done.

Update: After further digging, it's doesn't appear necessary to call finish in the child after all, since all it does is call exit. That means exec would work as well!