[jira] [Created] (HIVE-20761) Select for update on notification sequence table has retry interval and retries count too small.

["Sankar Hariappan (JIRA)" <ji...@apache.org>]

Sankar Hariappan created HIVE-20761:
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             Summary: Select for update on notification sequence table has retry interval and retries count too small.
                 Key: HIVE-20761
                 URL: https://issues.apache.org/jira/browse/HIVE-20761
             Project: Hive
          Issue Type: Bug
          Components: HiveServer2, Metastore
    Affects Versions: 4.0.0
            Reporter: Sankar Hariappan
            Assignee: Sankar Hariappan


Hive DDL's are intermittently failing with Error- Couldn't acquire the DB log notification lock because we reached the maximum # of retries: 5 retries
{code:java}
Error while processing statement: FAILED: Execution Error, return code 1 from org.apache.hadoop.hive.ql.exec.DDLTask. MetaException(message:Couldn't acquire the DB log notification lock because we reached the maximum # of retries: 5 retries. If this happens too often, then is recommended to increase the maximum number of retries on the hive.notification.sequence.lock.max.retries configuration :: Error executing SQL query "select "NEXT_EVENT_ID" from "NOTIFICATION_SEQUENCE" for update".)
2018-08-28 01:17:56,808|INFO|MainThread|machine.py:183 - run()||GUID=94e6ff4d-5db8-45eb-8654-76f546e7f0b3|java.sql.SQLException: Error while processing statement: FAILED: Execution Error, return code 1 from org.apache.hadoop.hive.ql.exec.DDLTask. MetaException(message:Couldn't acquire the DB log notification lock because we reached the maximum # of retries: 5 retries. If this happens too often, then is recommended to increase the maximum number of retries on the hive.notification.sequence.lock.max.retries configuration :: Error executing SQL query "select "NEXT_EVENT_ID" from "NOTIFICATION_SEQUENCE" for update".){code}
It seems, metastore operations are slow in this cluster and hence concurrent writes/DDL operations are failing to lock the row for update.
Currently, the sleep interval between retries is specified via the config *hive.notification.sequence.lock.retry.sleep.interval*. The default value is 500 ms which seems to be too small. Can we set higher values for sleep interval and retries count,

*hive.notification.sequence.lock.retry.sleep.interval=10s*

*hive.notification.sequence.lock.max.retries=10*



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