use threads;
use threads::shared;

my $tcount :shared = 0;

while(1){
    if($tcount < 4){
        print("Number of active threads : ".$tcount." processing incomming message\n");
        threads->create(processData);
    } else {
        print("Maximum number of threads reached. Waiting \n");
        sleep 1 until $tcount < 4;
        threads->create(processData);
    }
}

sub processData {
    $tcount++;
    #sleep(2);
    print "OK \n";
    $tcount--;
    threads->exit();
}