This is my understanding; When you use session_start(); in your script it sets a condition that will cause a session write of the contents of the $_SESSION array to the session repository (by default a file whose name contains the session ID) when the script has ended. At that time the record timestamp (file last modified date/time) should be modified or reset to the current time. To answer your question below, I believe technically the timestamp is very close to the script end time for a script containing a session_start() call (not the actual time of the session_start() call is executed). Periodically the gc (garbage cleanup) process is invoked, at which time all sessions whose timestamp is checked to see how old they are and if they precede the current timestamp minus the gc_maxlifetime value, they are to be removed from the repository. Notice that the processing above is accomplished when the script has ended (sent it's last output to the browser). By invoking the gc process at this time it never has a direct impact on the response time or the users experience, unless they are awfully fast with the mouse. I have in the past found that the GC routines are not invoked every invocation of a script, but rather a "probability" factor causes the GC routine to be invoked on only some percentage of the calls to session start to avoid adding needless load to the server (i.e. say 10% of all script executions may trigger a call to the GC routine). To offset this I had to make sure that when session_start() retrieved old session values (session_read), I had to add checks to make sure I wasn't reading an old session that had expired but had just not been cleaned up yet. You can learn a lot about sessions by coding and testing your own session_handler routines; http://www.php.net/manual/en/function.session-set-save-handler.php There are lots of other good tutorials in books on php programming. Warren Vail -----Original Message----- From: Suhas [mailto:psuhas@xxxxxxxxx] Sent: Monday, October 04, 2004 9:30 AM To: php-general Subject: Session.gc_maxlifetime? Hello, I just want to make sure that I understand this concept. When i read thr' docs, session.gc_maxlifetime specifies the number of seconds after which data will be seen as 'garbage' and cleaned up and default value is 1440. My guess is : A. 1440 seconds from last visit to the page (where session id is used), B. 1440 seconds from session_start() function call My general understanding is a session can be idle for 1440 seconds. If a php page tried to refer to a session which is been idle more than 1440 seconds, there is very little chance that page will access to session data. Can any one please explain or send links or more docs on this? Thanks in adv, Suhas -- Suhas Pharkute. -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
