Start session for second time or?

<?php 
   session_start();
   ...
?>

<?p开发者_Python百科hp 
   session_start();
?>

If I have some php script like this one. My question is should I escape to start session for second time or it is necessary?

You need not to start it again. As of now, calling session_start() while the session has already been started will result in an error of level E_NOTICE. Also, the second session start will simply be ignored.