# threads (same applies to running MCE::Child or parallel module of your choice)

my @workers = map threads->create(\&process_file), 1 .. $threads;

my @data = glob("data-* ??/data-*");
my $filecount = scalar(@data);
if ($filecount <= 0) {
    $queue->end;
    $_->join for @workers;
    die "there are no files to process";
}

say "Parsing $filecount files";
foreach $infile (@data) {
    $subdir = 1 if $subdir++ > $subdircount;
    $queue->enqueue([$infile, $subdir, $i++]);
}
$queue->end;
$_->join for @workers;