No Anonymous Sessions

The no_anon module eliminates the need for sessions for anonymous users

This has the potential to reduce the server load and/or database contention on busy sites, since crawlers do not create entries in the session table for every page view.

See how this positively affected a large site at reducing server load by eliminating anonymous sessions for Drupal 6.x.

Side effects

Some modules use the $_SESSION superglobal variable to store info for anonymous users will be affected by this module. If your modules use this only for logged in users, then it will not be an issue. Before you install this module, make sure that your modules do not depend on that.

This approach is known to cause the following features not to work:

1. The core Who's Online block

2. The core Throttle module

3. The anonymous user count in the Administration Menu module.

4. OpenID (see #873024: Core openid module also affected for more details.

For installation instructions, please refer to the README.txt file included with the tar ball.

Note that this module is for Drupal 6.x only. Drupal 7.x already has a similar feature in core.

Author

Khalid Baheyeldin of 2bits.com.

Based on an ">article by Marco Carbone, although the goal there is visitor privacy.