use Tie::File;

use threads;
use strict;

use constant NUMBER_OF_THREAD => 10;

$|++;

open(ACCOUNT, ">", "account.txt");
foreach (0..NUMBER_OF_THREAD) {
    print ACCOUNT "1000\n";
}
close(ACCOUNT);
tie my @account, "Tie::File", "account.txt" or die "cannot tie\n";

foreach (1..NUMBER_OF_THREAD) {
    my $kid = threads->create(\&thread_job, $_);
    $kid->detach();
}
untie @account;

sub thread_job {
    my $id = shift();
    print "I am a child, this is the name my parents gave me: ", $id, "\n";
    while (1) {
        $account[$id] -= 100;
        $account[$id] += 100;
    }
}