#! perl -slw
use strict;
use Time::HiRes qw[ time ];
use threads;
use Thread::Queue;

sub worker {
    my $tid = threads->tid;
    print "Thread: $tid started";
    my $Q = shift;
    while( my $workitem = $Q->dequeue ) {
        print "Thread: $tid processing workitem $workitem";
        sleep $workitem;
    }
    print "Thread: $tid ended";
}

our $WORKERS //= 10;
our $ITEMS   //= 1000;
our $MAXWORK //= 2;

my $Q = new Thread::Queue;
my @workers = map threads->create( \&worker, $Q ), 1 .. $WORKERS;

for ( 1 .. $ITEMS ) {
    sleep 1 while $Q->pending > $WORKERS;
    $Q->enqueue( rand( $MAXWORK ) );
    print "main Q'd workitem $_";
}
print "Main: telling threads to die";
$Q->enqueue( (undef) x $WORKERS );

print "Main waiting for threads to die";
$_->join for @workers;

##</code><code>##

[16:03:44.95] c:\test>ThreadPoolExample -WORKERS=4 -ITEMS=20 -MAXWORK=1
Thread: 1 started
Thread: 2 started
Thread: 3 started
main Q'd workitem 1
main Q'd workitem 2
main Q'd workitem 3
main Q'd workitem 4
main Q'd workitem 5
main Q'd workitem 6
main Q'd workitem 7
main Q'd workitem 8
Thread: 2 processing workitem 0.170745849609375
Thread: 1 processing workitem 0.852569580078125
Thread: 1 processing workitem 0.3243408203125
Thread: 1 processing workitem 0.4161376953125
Thread: 1 processing workitem 0.034759521484375
Thread: 1 processing workitem 0.488800048828125
Thread: 4 started
Thread: 3 processing workitem 0.927337646484375
Thread: 2 processing workitem 0.23193359375
main Q'd workitem 9
main Q'd workitem 10
main Q'd workitem 11
main Q'd workitem 12
main Q'd workitem 13
main Q'd workitem 14
main Q'd workitem 15
main Q'd workitem 16
main Q'd workitem 17
Thread: 3 processing workitem 0.3211669921875
Thread: 3 processing workitem 0.806793212890625
Thread: 3 processing workitem 0.1046142578125
Thread: 3 processing workitem 0.812042236328125
Thread: 3 processing workitem 0.38275146484375
Thread: 3 processing workitem 0.60479736328125
Thread: 1 processing workitem 0.225616455078125
Thread: 2 processing workitem 0.750457763671875
Thread: 4 processing workitem 0.132110595703125
main Q'd workitem 18
main Q'd workitem 19
main Q'd workitem 20
Main: telling threads to die
Main waiting for threads to die
Thread: 2 processing workitem 0.96856689453125
Thread: 2 ended
Thread: 3 processing workitem 0.59661865234375
Thread: 3 ended
Thread: 1 processing workitem 0.765777587890625
Thread: 1 ended
Thread: 4 ended