my $q = Thread::Queue->new();

my @threads;
for (1..MAX_WORKERS) {
   push @threads, async {
      while (my $job = $q->dequeue()) {
         do_job($job);
      }
   };
}

# Give work to the workers.
for my $job (...) {
   $q->enqueue($job);
}

# Signal the workers to exit.
$q->enqueue(undef) for 1..MAX_WORKERS;

# Wait for the workers to finish.
$_->join() for @threads;