my @array = (1 .. 20);

foreach my $x (@array){
	spawn($x);
}

...

sub spawn{
# the unless and : ? statements were too alien to me.
        my $x = shift;

        if ( ! $spawn_enabled ) {
                if ($children <= $min_child ){
                        $spawn_enabled=1;
                } elsif ( ! $spawn_enabled ) {
                        return;
                }
        }
        if ( fork() ){
                $children++;
                if ( $children > $max_child ){
                        $spawn_enabled = 0;
                }
                #printf "%d children running\n",$children;
        } else {
                my_child_work($x);
        }
}

sub my_child_work{
	my $x = shift;
	print "child x $x\n";
	sleep 1;
	exit;
}