PHP - ini_set('session.gc_maxlifetime', 5) - Why it doesn't end the session?

Question

The PHP script is as follows:

Answer 1

Read the manual (emphasis mine):

session.gc_maxlifetime specifies the number of seconds after which data will be seen as 'garbage' and potentially cleaned up. Garbage collection may occur during session start (depending on session.gc_probability and session.gc_divisor).

In the same page:

session.gc_divisor coupled with session.gc_probability defines the probability that the gc (garbage collection) process is started on every session initialization. The probability is calculated by using gc_probability/gc_divisor, e.g. 1/100 means there is a 1% chance that the GC process starts on each request. session.gc_divisor defaults to 100.

Now do the math and see that it's not very likely the GC will be called on each request.

You should store the in the session a variable that saves the time of the last activity of the user and use that instead of the session is logically "active". Don't rely on garbage collection.