These suggestions seem to be quite satisfactory.   Many thanks.

To answer the question of “scheduling:   “ at the moment, there isn’t any.”   The Perl program will simply launch n children and wait (sometimes hours) for any one of them to finish, then start the next one on a prescribed list (table).   (Stupidly simple, and absolutely essential.   Maybe someday it will get fancier, but then again, ts never was.)   This should “plug the leak in the dike,” and that’s the only thing I need The Camel to do now.   To replace an unreliable, unknown utility with a reliable beast of burden (having a large, friendly humph).