PCNTL-PHP对守护进程的好处是什么？

I was researching and trying to do a daemon process using php, I found my self compelled to recompile PHP to enable PCNTL. Then I started to do some tests. I forked the single orphan example :

#!/usr/bin/env php
<?php
$pid = pcntl_fork();

if ($pid === -1) {
    echo("Could not fork! 
");die;
} elseif ($pid) {
    echo("shell root tree 
");
} else {
    echo "Child process 
";

    chdir("/");

        fclose(STDIN);
        fclose(STDOUT);
    fclose(STDERR);
    $STDIN = fopen('/dev/null.txt', 'r');
    $STDOUT = fopen('/dev/null.txt', 'wb');
    $STDERR = fopen('/dev/null.txt', 'wb');

    posix_setsid();
    while(1) {
        echo ".";
        sleep(1);
    }
}

then I ran the script :

$cd /var/www
$./test.php

every thing was going well, the file /dev/null.txt cleared and was being updated in the infinite loop each 1 second.

Then I wondered about the benefit of PCNTL, so I changed the code :

#!/usr/bin/env php
<?php

fclose(STDIN);
fclose(STDOUT);
fclose(STDERR);

$STDIN = fopen('/dev/null.txt', 'r');
$STDOUT = fopen('/dev/null.txt', 'wb');
$STDERR = fopen('/dev/null.txt', 'wb');

while(1) {
    echo ".";
    sleep(1);
}

Both of the previous examples gave me the same results. Have I missed something ? Can you guide me