ORA-00031:- session marked for kill
Cause:- The session specified in an ALTER SYSTEM KILL SESSION command
cannot be killed immediately (because it is rolling back or blocked on a
network operation), but it has been marked for kill. This means it will be
killed as soon as possible after its current uninterruptable operation is done.
Action:- No action is required for the session to be killed, but further
executions of the ALTER SYSTEM KILL SESSION command on this session may cause
the session to be killed sooner.