my $lock = get_lock();
# --- critical stuff ---
release_lock( $lock );

sub get_lock {
    my $server = shift || "localhost";
    my $port = shift || 10101;
    my $retry_count = 0;
    my $lock;
#sometimes the port needs a second, so we let it retry.
	while ( $retry_count++ < 30 ) {
	    if( $lock = IO::Socket::INET->new(Proto => "tcp",
					      PeerAddr => $server,
					      PeerPort => $port) ) {
		$lock->autoflush(1);
		last;
	    }
	}
    print $lock "\n";
    until ( <$lock> ) { sleep(1) }
    return $lock;
}

sub release_lock {
    my $lock = shift || return;
    return close $lock;
}