fork is fraught in perl without it really being perl's fault. I had recently endeavored to do some multitasking project that way and became convinced that the implementation is not worth the trade-offs, the first being that it must occur in an eval/die pair. My source looks about like yours, and my results were just about as unsatisfying as well. This is about where I dealt with it first: Re^2: using online translation engines with perl.

There were a couple posts on that thread that showed how to kill the processes. I used a different way to get done what I needed.