use Apache::SubProcess;

    my $pid = fork;
    if (defined $pid && !$pid) {
        Apache->request->cleanup_for_exec();

        $pid = fork;
        if (defined $pid && !$pid) {

            close STDERR;
            close STDIN;
            close STDOUT;

            use POSIX();
            POSIX::setsid();

            ##########
            # do long running stuff here
            ##########

            CORE::exit;
        }
        else {
            CORE::exit;
        }
    }
    waitpid($pid, 0);