Impala query error

[#1]

Hi，I'm trying to connect the impala on cdp throught JDBC,but it didn't work.It just show:

[Cloudera][ImpalaJDBCDriver](500051) ERROR processing query/statement. Error Code: 0, SQL state: Exec() rpc failed: Remote error: Service unavailable: ExecQueryFInstances request on impala.ControlService from 21.97.66.145:38012 dropped due to backpressure. The service queue contains 0 items out of a maximum of 2147483647; memory consumption is 0.
, Query: SELECT 1 as `expr_0`.
java.sql.SQLException: [Cloudera][ImpalaJDBCDriver](500051) ERROR processing query/statement. Error Code: 0, SQL state: Exec() rpc failed: Remote error: Service unavailable: ExecQueryFInstances request on impala.ControlService from 21.97.66.145:38012 dropped due to backpressure. The service queue contains 0 items out of a maximum of 2147483647; memory consumption is 0.
, Query: SELECT 1 as `expr_0`.
at com.cloudera.impala.hivecommon.api.HS2Client.pollForOperationCompletion(Unknown Source) ~[?:?]
at com.cloudera.impala.hivecommon.api.HS2Client.executeStatementInternal(Unknown Source) ~[?:?]
at com.cloudera.impala.hivecommon.api.HS2Client.executeStatement(Unknown Source) ~[?:?]
at com.cloudera.impala.hivecommon.dataengine.HiveJDBCNativeQueryExecutor.executeQuery(Unknown Source) ~[?:?]
at com.cloudera.impala.hivecommon.dataengine.HiveJDBCDSIExtQueryExecutor.execute(Unknown Source) ~[?:?]
at com.cloudera.impala.jdbc.common.SStatement.executeNoParams(Unknown Source) ~[?:?]
at com.cloudera.impala.jdbc.common.BaseStatement.executeQuery(Unknown Source) ~[?:?]
at com.cloudera.impala.hivecommon.jdbc41.Hive41Statement.executeQuery(Unknown Source) ~[?:?]

Any help with this impala error is much appreciated.

[#2]

@WuHua 

Can you please try to add this property and re-run query?

 Add
--control_service_queue_mem_limit=200M
to
"Impala Daemon Command Line Argument Advanced Configuration Snippet (Safety Valve)"

Thanks !