[jira] [Updated] (HIVE-15965) Metastore incorrectly re-uses a broken database connection

["Mass Dosage (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HIVE-15965?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Mass Dosage updated HIVE-15965:
-------------------------------
    Attachment: hive.log

Log file from a test that reproduces the issue

> 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: storage-2.2.0
>            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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