How to prevent sessions from being flushed to disk?

Hi,

We have an ajax process that is sending multiple requests asynchronously to some controller actions. These actions need to read the session, but we don't want the session to be flushed back to disk when the action completes.

The reason this capability is needed is that there may be multiple requests in-flight from a single browser (either with or without browser tabs open). These multiple concurrent requests can cause inconsistencies in the session, when run with a parallel/fastcgi web server.

How can we tell Rails not to flush a session back to disk when the action finishes?

Thanks,

David