Session gets destroyed

[eluser]himself[/eluser]
Hi

My sessions keeps getting destroyed, e.g the user gets logged out.

I simply cannot figure out why.

Mysql data (which prob gets messed up now):

Code:

SELECT session_id, last_activity, length(user_data) FROM ci_sessions;
+----------------------------------+---------------+-------------------+
| session_id                       | last_activity | length(user_data) |
+----------------------------------+---------------+-------------------+
| 42fc1695a00dad0193ac7a6a2bfa72b1 |    1245307085 |               334 |
| 89911d917cd41556d223b5201c0d2974 |    1245307397 |               334 |
| ec1e444422ec19acff69c8d1386563f1 |    1245307397 |                 0 |
+----------------------------------+---------------+-------------------+

Th ip and user agent is not the problem, and the above should show that the cookie size (4kb) is not the problem.
My "ci-session-refresh-interval" is set at 300, so looking at the timestamp, it seems that it fails on the first attempt.

Normally the session works just fine, but not in this scenario:

I have a long list of images to be processed, there is not enough memory to process them all in one go, so i've made a form that, through javascript, submits itself, processes an image, submits itself, .... until its done.

From the sqldump you can se that it creates a new session_id.

From tampering a bit with the Session library, i can see that it's the session_id that (at some point) gets changed, so the session library creates a new on, meaning.. the user gets logged out.

Can anyone help point out where the problem could be, I know its a bit vague, but, hey... shoot :-)
Sincerely, Jonas

[eluser]gtech[/eluser]
The sessionid is supposed to get regenerated after every 5 minutes (or 300 seconds), this is a security measure to make session hijacking more difficult. But I dont understand why that would log your user out? the session data is still there and you can still retrieve it, as a copy is made when the new id is generated.

Code:

// session data can still be retrieved after the sess_id has changed
$this->session->userdata('<variable name>');

maybee the session is expiring?, see sess_expiration in the config. this would cause the session to be destroyed.

[eluser]TheFuzzy0ne[/eluser]
You don't have to process all of your images at the same time. You can just loop through each of them, reading them from the hard drive.

Is this just a random thing, or does it only happen when you run a certain controller, or a certain condition is met? What are the contents of the cookie? Is it encrypted? Do you still get the problem when you disable database sessions?