I am playing with long polling and trying to stop the script started by an AJAX call if a new request happens.
This is the PHP code that is started by an AJAX request:

```
$checker = $_SESSION['checker'] = time();

while (true) {
    if ($checker != $_SESSION['checker']) {
          $out = 'new one started';
          break;
     }

    if (some other condition) {
           $out = 'smth done or happend';
           break;
    }

    sleep(3); 
}

echo $out;

```

I have been doing some logging and it looks like `$_SESSION['checker']` is not updated, so if I run same script (which should change the `$_SESSION['checker']` variable), the while loop in the previously started script will still see the old `$_SESSION['checker']`. Why is it not updated?