Processing large directory trees in parallel is an interesting problem, as "a directory with huge number of files" could be split up differently than "a huge number of branches" depending on one's approach. The method above should work with either (and is even more general than Gnu "parallel").

File::Find can be made to work in parallel, but it is ugly. Cleaner to start new as we did here. I keep meaning to blog about this alternate solution (have post half-written) and turn it into a CPAN module...