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New module: Session expire

A new module that helps with busy sites has been released.

This is the session expire module.

Problem

On busy sites, the number of rows in Drupal's sessions table can be really high. We saw sites with 1.7 million rows in it!

Drupal's core relies on PHP garbage collection to do this cleanup, but the options are sometimes not set correctly in php.ini, and vary from distro to distro, so the cleanup may not kick in at all. Moreover, the cleanup can be triggered by normal page views.

Solution

This module makes session cleanup more predictable and consistent, and also more configurable. By using Drupal's hook_cron, we avoid the uncertainity of PHP's garbage collection and its susceptibility to option settings.

Options are provided for : how often should the cleanup be attempted, the age of the sessions to be expired, and whether to expire only anonymous sessions or both anonymous and authenticated sessions.

A watchdog message notice is logged with the number of rows deleted from the sessions table.

Download

You can download the module from the session expire module project page on Drupal.org.

Sponsors

Screenshot

This screenshot shows the options available in the module:

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Thank you!

Submitted by Chris Bryant (not verified) on Mon, 2007/11/05 - 21:05.

Thank you for the writeup and sharing this module! We had been running into the same problem (450,000 sessions every 24 hours) and were doing a scheduled cleanup with cron, but it's much better being integrated with Drupal as such :)

Would it make sense to add a feature to the module where it prunes the sessions once they get over a certain number? That way if you get a ton of extra traffic from Digg, etc. within a short amount of time, the sessions can be pruned before the performance starts to suffer. Or is there a reason you wouldn't take that approach?

Chris

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Actuall, tried to push it in core

Submitted by Khalid on Mon, 2007/11/05 - 23:35.

I actually tried to push this functionality into Drupal core, as per #72856. It was not well received, so I created this module.

Perhaps someone will see the light, and this can be pushed into Drupal 6, replacing the PHP garbage collection stuff. If others think this is a good idea, I can create a patch for this, removing the stuff in session.inc and .htaccess too.

Adding an option for number of rows is more involved. We can know how many are there in the table using a COUNT(*), but how do prune in a way that would say "delete X rows"?
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2bits -- Drupal consulting

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