9d2f8043_Troubleshooting_Impala__Recommendation
[Symptom] Impala fails to start up, with the impalad logs referring to errors connecting to the statestore service and attempts to re-register. [Explanation] A large number of databases, tables, partitions, and so on can require metadata synchronization, particularly on startup, that takes longer than the default timeout for the statestore service. [Recommendation] 
Configure the statestore timeout value and possibly other settings related to the frequency of statestore updates and metadata loading. See Increasing the Statestore Timeout and Scalability Considerations for the Impala Statestore.
Troubleshooting Impala