Major Description
The TabletServer watches the active scans presently running and "stops" any that have not had any client communication in the time set by Property.TSERV_SESSION_MAXIDLE.
The SessionManager reads the last accessed time for each Session (which is updated by the Thrift RPC implementation). When the SessionManager finds a Session which hasn't been updated within the required time limit, it calls cleanup on the Session (which ultimately calls cancel on the ScanTask inside of the Session) and removes it from its internal state.
Presently, there is absolutely no logging on the server side when this occurs which would make it very difficult, if not impossible, to debug this situation and determine that TServer reaped the Session because it was inactive.
We should, at a minimum, have logging so that someone debugging the system for a Session that was closed could validate that it was expected system functionality.
