Questions about the garbage collection mechanism of the session

About the session garbage collection mechanism problem!

seession.gc_maxlifetime=1440;
Seesion.gc_probalility=1;
session.gc_divisor=1000;

I understand that 1 of thousands of users may use the session, but if it is the probability of a 1-percent
, that's not right, the session how to do ah?? To ask for a satisfactory explanation.

------Solution--------------------
An explanation of the quote:
The principle of PHP processing session is no exception, but in the specific way of implementation, but different. This is because, because of PHP working mechanism, it does not have a background thread, to periodically scan the session information and determine whether it is invalid. The solution to this is that when a valid request occurs, PHP determines whether to invoke a GC (garbage Collector), depending on the probability. The GC's job is to scan all session information, subtracting the last modification time of the session (modified date) with the current time, with the configuration parameter (config option) session.gc_ The Maxlifetime value is compared, and if the lifetime has exceeded Gc_maxlifetime, the session is deleted. This is easy to understand, because if the GC code is called every time the request is made, PHP will be inefficient. This probability depends on the value of the configuration parameter Session.gc_probability/session.gc_divisor (which can be modified by the php.ini or Ini_set () function). By default, session.gc_probability = 1,session.gc_divisor=100, which means that there is a 1% possibility to start the GC.
These three parameters, Session.gc_maxlifetime/session.gc_probability/session.gc_divisor can be modified by the php.ini or Ini_set () function. Remember, however, that if you use the Ini_set () function, you must call Ini_set () at the beginning of each page.

Read the full text: http://koda.iteye.com/blog/319605

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