How to prevent sessions from being flushed to disk?


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?