Idle Session Timeouts

An idle session timeout allows a use connection to close automatically after a specified period of inactivity.A database administrator can use it to enforce closure of old connections that have become inactive, to reduce unnecessary consumption of resources.It can also be used by application and tools developers as an alternative to writing their own modules for controlling connection lifetime.

By default, the idle timeout is not enabled.No minimum or maximum limit is imposed, but a reasonably large period — such as a few hours — is recommended.

How the Idle Session Timeout Works

When the user API call leaves the engine (returns to the calling connection) a special idle timer associated with the current connection is started
When another user API call from that connection enters the engine, the idle timer is stopped and reset to zero
If the maximum idle time is exceeded, the engine immediately closes the connection in the same way as with asynchronous connection cancellation:
- all active statements and cursors are closed
- all active transactions are rolled back
- The network connection remains open at this point, allowing the client application to get the exact error code on the next API call.The network connection will be closed on the server side, after an error is reported or in due course as a result of a network timeout from a client-side disconnection.

Note

Whenever a connection is cancelled, the next user API call returns the error isc_att_shutdown with a secondary error specifying the exact reason.Now, we have

isc_att_shut_idle: Idle timeout expired

in addition to

isc_att_shut_killed: Killed by database administrator
isc_att_shut_db_down: Database is shut down
isc_att_shut_engine: Engine is shut down