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https://issues.apache.org/jira/browse/HIVE-15965?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15942014#comment-15942014
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Pengcheng Xiong commented on HIVE-15965:
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Hello, I am deferring this to Hive 3.0 as we are going to cut the first RC and
it is not marked as blocker. Please feel free to commit to the branch if this
can be resolved before the release.
> Metastore incorrectly re-uses a broken database connection
> ----------------------------------------------------------
>
> Key: HIVE-15965
> URL: https://issues.apache.org/jira/browse/HIVE-15965
> Project: Hive
> Issue Type: Bug
> Components: Metastore
> Affects Versions: 2.1.1
> Reporter: Mass Dosage
> Attachments: hive.log
>
>
> *Background*
> In our setup we have a shared standalone MetaStore server running on EMR that
> is accessed by various clients (Hive CLI, HiveServer2, Spark etc.) and
> connects to an external MariaDB database for the MetaStore DB. It came to our
> attention that MetaStore (or rather the underlying DataNucleus / BoneCP
> combo) will keep re-using the same DB connections even when those get
> suddenly closed for a reason that renders them unusable.
> For instance, due to a bug in the MariaDB JDBC driver v1.3.6 (see
> https://jira.mariadb.org/browse/CONJ-270), a huge query including over 8
> thousand parameter placeholders (e.g. partition IDs in case of a
> {{get_partitions_by_expr}} function call)
> will yield a {{java.nio.BufferOverflowException}} and cause the SQL
> connection be closed by the driver itself.
> This will ultimately result in the abortion of all further MetaStore Thrift
> calls due to the failure of {{bonecp.ConnectionHandle.prepareStatement()}}.
> Such scenarios will be then caught by DataNucleus and translated to an
> appropriate {{JDOException}}, only to be "ignored" by the
> MetaStore.{{RetryingHMSHandler}} will, of course, continue retrying the
> failing operation, but this is already pointless by that time since they will
> invariably fail as long as the SQL connection remains closed. Please see the
> attached MetaStore log [^hive.log] for details
> (captured from Hive 2.1.1 running on Windows in Eclipse IDE).
> *Proposed behavior*
> We suggest that MetaStore should automatically renew the DB connection
> whenever:
> * The connection gets closed by one of the underlying frameworks
> (DataNucleus, BoneCP, JDBC driver); or
> * Query timeout is detected.
> This feature should be optional and configurable (disabled by default for
> backward compatibility). Reconnection failures could probably be treated as
> fatal errors and cause the immediate termination of MetaStore.
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