use strict ; use warnings ;

use threads ;

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

for (1..5) {
  for (1..2) {
    push @children, threads->create(\&sub_thread, @array) ;
  } ;

  while (@children) {
    my $child = shift(@children) ;
    push @results, $child->join() ;
  } ;
} ;

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

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

  sleep (2) ;

  return 'whatever' ;
} ;

##</code><code>##

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" ;
} ;

##</code><code>##

use strict ; use warnings ;

use threads ;
use Thread::Queue ;

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

my $param_queue  = new Thread::Queue ;
my $result_queue = new Thread::Queue ;

my $c =  2 ;    # concurrent threads
my $n = 10 ;    # amount of work
my @children ;

for (1..$c) {   # Start the threads
  push @children, threads->create(\&sub_thread) ;
} ;  

for (1..$n) {   # Dispatch the work
  $param_queue->enqueue([@array]) ;
} ;

for (1..$n) {   # Collect the results
  push @results, $result_queue->dequeue() ;
} ;

$param_queue->enqueue((undef) x $c) ;  # Signal the threads to stop

foreach (@children) {   # Collect the terminated threads
  $_->join() ;
} ;

sub sub_thread {
  my $task = 0 ;
  my $tid = threads->tid() ;

  print "child $tid: started" ;

  while (my $p = $param_queue->dequeue()) {
    $task++ ;
    my @temp = @$p ;

    print "child $tid/$task: @temp\n" ;

    sleep(rand(2)+2) ;

    $result_queue->enqueue("whatever from child $tid/$task") ;

    print "child $tid/$task: done\n" ;
  } ;

  print "child $tid: terminated\n" ;
} ;