use warnings;
use strict;

use IPC::Shareable;

$SIG{INT} = sub { exit; };

my $href = {count => 0};

my $ipc = tie 
            $href, 
            'IPC::Shareable', 
            undef, 
            { destroy => 1 };

for (1 .. 3) { 
    unless (fork()){
        while (1){
            $ipc->shlock();
            $href->{count}++;
            $href->{pid} = $$;
            $ipc->shunlock();
        }
        exit;
    } 
}

while (1) {
    next if ! defined $href->{pid};
    print "pid: $href->{pid}, count: $href->{count}\n";
    sleep 1;
} 

##</code><code>##

pid: 19062, count: 1
pid: 19062, count: 1472
pid: 19063, count: 3070
pid: 19063, count: 4771
pid: 19062, count: 6548
pid: 19062, count: 8179
pid: 19062, count: 10070
pid: 19064, count: 11817
^C