#!/usr/bin/perl

use Parallel::ForkManager;

my $max_threads = 5;

my $fork_mgr = new Parallel::ForkManager($max_threads);

$fork_mgr->run_on_finish
(
    sub
    {
        my($child_pid, $exit_code, $child_id, $exit_signal, $core_dump) = @_;

        # Code to store the results from each thread go here.
    }
);

foreach my $item (@big_list)
{
    $fork_mgr->start($url_ent) and next URL
    
    # Code in this block will run in parallel
    my $result = do_stuff($item);
    
    # Store the final result. The value you pass to finish will be
    # received by the sub you defined in run_on_finish
    $fork_mgr->finish($result);
}

$fork_mgr->wait_all_children();

# Now all child threads have finished,
# your results should be available.