use strict;
use warnings;
use feature qw( say );

use Parallel::ForkManager qw( );

sub RunChild {
    my ($item) = @_;
    exit($item);
}

{
    my $pm = Parallel::ForkManager->new(5);

    $pm->run_on_finish(sub {
        my ($pid, $exit_code, $ident, $signal, $core) = @_;
        say $exit_code;
    });

    for (1..10) {
        my $pid = $pm->start and next;
        RunChild($_);
        $pm->finish;
    }

    $pm->wait_all_children;
}