#!/usr/bin/env perl

use strict;
use warnings;

my @iterations = map { 10 ** $_ } 0 .. 10;
my $timeout = 2;    

for my $iterations_this_loop (@iterations) {
    eval {
        local $SIG{ALRM} = sub { die "TIMEOUT: $iterations_this_loop\n" };
        alarm $timeout;

        for (0 .. $iterations_this_loop) {
            # Processing here
        }

        alarm 0;
    };

    if ($@) {
        die $@ unless $@ =~ /^TIMEOUT: \d+/;   # propagate unexpected errors
        print $@;
        next;
    }
    else {
        print "ENOUGH TIME: $iterations_this_loop\n";
    }
}

##</code><code>##

$ pm_long_for_alarm.pl
ENOUGH TIME: 1
ENOUGH TIME: 10
ENOUGH TIME: 100
ENOUGH TIME: 1000
ENOUGH TIME: 10000
ENOUGH TIME: 100000
ENOUGH TIME: 1000000
ENOUGH TIME: 10000000
TIMEOUT: 100000000
TIMEOUT: 1000000000
TIMEOUT: 10000000000