Thanks a lot! That's exactly what I was trying to write. I'm a little ashamed because it seems I should have been able to come up with it myself.

There is one funny thing, though: If I comment out the "for my $val2 (@array2) {..." and the corresponding closing curly bracket (and change $val2 to a constant like "step2"), it breaks with Cannot start another process while you are in the child process at .../perl/lib/perl5/Parallel/ForkManager.pm line 463. Not that I would want that - in my case I need the two nested loops. It's just that I don't know what is happening there. I mean, in the nested loop, I would have assumed I was in the 1st child process, which is itself the parent of the 2nd child process, right?