谷歌浏览器：会话启动时，PHP代码将执行两次

Question

I need to set a dynamic id for every document load. This ID should be set in PHP. Now, when i set a session_start(), the php code would be executed twice because the ID-code in generated document source differs from the same code in the alerted script variable. There are no runtime errors.

What's wrong with this code and how can i prevent the session to re-execute my code after session_start() ?

And when the code would be executed twice (var idvar contains a different value) why the heck is alert executed only once?

I simplified the script so you can try for your self:

<?php

// Session start generates two different ID's
session_start();

// Create ID
$time = microtime(1);
$parts = explode('.', (string)$time);
$idvar = strtoupper(strrev(dechex($parts[0]) . dechex($parts[1]))) . dechex(rand());

?>

<script>
    // Contains a new generated ID after session_start()
    var IDvr = '<?php print $idvr; ?>';
    alert(IDvr);
</script>

Screenshots:

Answer 1

Try move the id initialization just before session_start() i suspect it related on how things executed in php after session_start().

Edit still unable to reproduce it