This is thrown if the time between RPC calls from the client to RegionServer exceeds the scan timeout.
For example, if Scan.setCaching is set to 500, then there will be an RPC call to fetch the next batch of rows every 500
.next() calls on the ResultScanner
because data is being transferred in blocks of 500 rows to the client. Reducing the setCaching value may be an option, but setting this value too low makes for inefficient
processing on numbers of rows.