#!/usr/bin/env perl

use strict;
use warnings;

our $flag = 0;

$SIG{ALRM} = \&Watchdog;

sub Watchdog {
    print "--- Tick ".$main::flag++."---\n";
    if ($main::flag >3) {
        print "--- Bark! Bark! ---\n";
        exit 1;
    }
    alarm 1;
}

alarm 1;

while(1) {
    print "main loop...\n";
        while(1){};
    print "done\n";
    $main::flag = 0;
}