Actually, that's a pretty good technique (which I was thinking of before I scrolled down to see yours!).

The limit stuff applies per process, so the kids would get a reset counter for all of them.

About the only thing this messes up is the "who's yer daddy?" situtation. In fact, they'd be children of init(8), so they'd charge not to your process, but to the great granddaddy when they died. Pretty slick.

If the trigger was strictly on CPU time, you could just do this:

use List::Util qw(sum);
while (1) {
  if (sum(times) > 30) { # have I used more the 30 CPU seconds?
    fork and exit; # carry on, my wayward son, there'll be peace when 
+you are done...
  }
  ... rest of processing here ...
}
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-- Randal L. Schwartz, Perl hacker