#!/usr/bin/perl -w

use Thread;
use Thread::Semaphore;

my $max_parallel_jobs = 3;
my $users_file = "users.txt";

open(USERS, "<$users_file") or die "Could not read $users_file!\n";
my @users = <USERS>;
close(USERS);
my $total_jobs = $#users;

my $sem = Thread::Semaphore->new($max_parallel_jobs);

my @output=();

for my $job (0..$total_jobs){
    $sem->down();
    my $thread = Thread->new(\&test_user, $users[$job]);
    $thread->join();
}

while(<@output>){
    print "output: $_";
}

sub test_user
{
    chomp($_[0]);
    print "USER: $_[0]\tist jetzt an der Reihe!\n";
    push(@output, $_[0]);
    $sem->up();
}