session.gc_maxlifetime not working for me

0 votes
asked Jan 14, 2010 by bharanikumar

i want to set session time out limit by 3 min ,

i have used this in the page

ini_set("session.gc_maxlifetime", "50"); not working

Solution for this

if (isset($_SESSION['LAST_ACTIVITY']) && (time() - $_SESSION['LAST_ACTIVITY'] > 1800)) { // last request was more than 30 minates ago session_destroy(); // destroy session data in storage session_unset(); // unset $_SESSION variable for the runtime } $_SESSION['LAST_ACTIVITY'] = time(); // update last activity time stamp

2 Answers

0 votes
answered Jan 14, 2010 by gumbo

The unit for the session.gc_maxlifetime value is seconds. So you would need to set it to 180 seconds to express 3 minutes.

But besides that, session.gc_maxlifetime is not reliable (see this post for an explanation). You should better implement that on your own to have your session expired after exactly 3 minutes.

0 votes
answered Jan 21, 2016 by david-gausmann

Three variables are used to define the garbage collection behavior of PHP session variables:

  1. session.gc_maxlifetime is the lifetime in seconds for the session files (default value: 1440 = 24 minutes)
  2. session.gc_probability is the nominator for the probability to execute the garbage collector (default = 1)
  3. session.gc_divisor is the denominator for the probability to execute the garbage collector (default = 100 or 1000)

The nominator and denominator are used together to determine the probability (nominator / denominator). So when session.gc_probability is 1 and session.gc_divisor 100 this is 1 / 100 = 1 %. So 1 % of every page visit (= every session_start call) the garbage collector is executed.

If you want to test how your session expires, you need to set session.gc_probability and session.gc_divisor to 1, so each page visit will cause the garbage collector to run. Furthermore you need to use two different browsers for the test. The session of the first browser becomes cleaned when you visit your page with the second browser (and the session of the first browser is timed out). In my tests, when you use only one browser, the session becomes automatically extended although it is outdated.

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