#!/usr/bin/perl -lw
use strict;
use threads;
use threads::shared;
use threads::Q;

my $semStdout :shared;
$|++;

sub tprint{
    my $str = shift;
    my $tid = threads->tid();
    lock $semStdout;
    print "[$tid] $str";
}

sub processrefsthread {
    my $Q = shift;
    tprint 'Starting';
    while( my $job = $Q->dq() ) {
        tprint "processing job $job";

        my $d = int(rand(5));
        for my $i (0 .. $d * 500000) {
            my $j = $i * $d;
            $j = int(rand($j));
        }
    }
    tprint 'Ending';
}

our $T //= 4;

my $Q = threads::Q->new( $T * 4 ); ## Q self-limits to 4*$T elements

my @threads = map threads->new( \&processrefsthread, $Q ), 1 .. $T;
$Q->nq( $_ ) for 1 .. 50;
$Q->nq( (undef) x $T );
$_->join for @threads;