I recently installed cloudera using cloudera manager . While working with hive( executing command like -"show databases;") getting :-
SemanticException org.apache.hadoop.hive.ql.metadata.HiveException: java.lang.RuntimeException: Unable to instantiate org.apache.hadoop.hive.ql.metadata.SessionHiveMetaStoreClient .
My Hive metastore is also down .(After restarting it is in good state and later on it goes to bad health).
Message from /var/log/hive/hadoop-cmf-hive-HIVEMETASTORE-master.rmd.com :-
... 48 more
Caused by: java.io.EOFException: Can not read response from server. Expected to read 4 bytes, read 0 bytes before connection was unexpectedly lost.
... 65 more
2017-12-13 11:38:33,146 INFO org.apache.hadoop.hive.metastore.HiveMetaStore: [Thread-2]: Shutting down hive metastore.
According to the log, there is an issue with the communication with the MySQL used as backend database to Hive.
Can you check the health status of mysql, e.g. try to connect from the host you are running the Hive Metastore to DB with mysql client, using the same credentials you have configured in Cloudera Manager for Hive Metastore and try to query some tables.
Assuming that during installation you have completed all steps, especially "Create Hive Metastore Database Tables"