PHP: Why PHP 5.4's session_status() is better than session_id() for determining if a PHP session is active. Also shows how to resolve multiple session restarting.

session_status_vs_session_id.php

<?php

ob_start();

session_start();

var_dump(session_status());
var_dump(PHP_SESSION_ACTIVE);
var_dump(session_status() == PHP_SESSION_ACTIVE); //(true means active, false means no)
var_dump(session_id() !== '');

session_write_close();

var_dump(session_status());
var_dump(PHP_SESSION_ACTIVE);
var_dump(session_status() == PHP_SESSION_ACTIVE); //(true means active, false means no)
var_dump(session_id() !== '');

session_start();
session_regenerate_id(false);

// session_destroy();

//this will prevent multiple session cookies
if(defined('SID')){ //SID is the same as session_id(), they will always be true as long as you have used session_start() at least once in the script runtime
	$headers =  array_unique(headers_list()); 
	$cookie_strings = array();
	foreach($headers as $header){
		if(preg_match('/^Set-Cookie: (.+)/', $header, $matches)){
			$cookie_strings[] = $matches[1];
		}
	}
	header_remove('Set-Cookie');
	foreach($cookie_strings as $cookie){
		header('Set-Cookie: ' . $cookie, false);
	}
}

ob_flush();