my $r = shift;
$r->send_http_header('text/plain');

defined (my $kid = fork) or die "Cannot fork: $!\n";
if ($kid) {
    waitpid($kid,0);
}
else {
    defined (my $grandkid = fork) or die "Kid cannot fork: $!\n";
    if ($grandkid) {
        CORE::exit(0);
    }
    else {
        # code here
        # do something long lasting
        CORE::exit(0);
    }
}