use strict ; use warnings ;

use threads ;
use Thread::Queue ;

my @array = qw(a b c d e f g h);
my @results;

my $finished_queue = new Thread::Queue ;

my $c = 2 ;     # Number active at once
my $n = 10 ;    # Total number to dispatch
my $m = $n ;    # Number to collect

while ($m) {
  while ($n && $c) {
    my $child = threads->create(\&sub_thread, @array) ;
    $n-- ;
    $c-- ;
  } ;

  my $tid = $finished_queue->dequeue() ;
  my $child = threads->object($tid) ;
  push @results, $child->join() ;

  $m-- ;
  $c++ ;
} ;

sub sub_thread {
  my (@temp) = (@_) ;

  my $tid = threads->tid() ;
  print "child $tid: @temp\n" ;

  sleep(rand(2)+2) ;

  $finished_queue->enqueue($tid) ;

  print "child $tid: finished\n" ;
  return "whatever from child $tid" ;
} ;