If your Perl is not built with threads support, no problem. GrandFather's queue demonstration is possible using MCE::Hobo and MCE::Shared. Notice the similarity.

use strict;
use warnings;
use MCE::Hobo;
use MCE::Shared;

my $workQueue  = MCE::Shared->queue();
my $doneQueue  = MCE::Shared->queue();
my $numWorkers = 4;

MCE::Hobo->create(sub{DoWork($workQueue, $doneQueue)}) for 1 .. $numWo
+rkers;

for (1 .. 10000) {
    my $work = int(rand(10000));
    $workQueue->enqueue($work);
}

$workQueue->end();

my $count_done = 0;

while () {
    my $result = $doneQueue->dequeue();
    last if (!$result && ++$count_done == $numWorkers);
    print "$result\n" if $result;
}

$_->join() for MCE::Hobo->list;

exit;

sub DoWork {
    my ($work, $done) = @_;
    while (my $item = $work->dequeue()) {
        $done->enqueue($item) if $item >= 10 && $item <= 20;
    }
    $done->enqueue(0);
}
[download]

Regards, Mario