Major Description
In the case that a complex query (aggregation/join) is passed to external LLAP client, the query result is first saved as a Hive temp table before being read by LLAP to client. Currently the HS2 connection used to fetch the LLAP splits is closed right after the splits are fetched, which means the temp table is gone by the time LLAP tries to read it.
Try to keep the connection open so that the table is still around when LLAP tries to read it. Add close methods which can be used to close the connection when the client is done with the query.