HHVM上的session_start（）函数比php5或php7慢

Question

for this simple code:

<?php
$time_start = microtime(true);

session_start();
echo session_id();

$time_end = microtime(true);
$time = ($time_end - $time_start)*1000;
echo "<br> Time to get uid: $time milliseconds";

?>

When I run it in php7 or php5 with Apache server, the run time is around one millisecond but my machine with HHVM takes 60-100ms to execute this. I tried changing the handler to Redis rather than files but got it more than 100ms. I also tried deleting all other sessions, the same. Any idea?

Answer 1

I figured out the problem. In my own system the longer time is due to large variables I saved in my session, while a new session in other systems starts as an empty session.

For future reference, session_start() run-time depends on variables the system needs to load and make them available as a session; so less data you put on your session the faster your overall page speed will be, if you're using sessions in your php code.