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From "Vaibhav Gumashta (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-14187) JDOPersistenceManager objects remain cached if MetaStoreClient#close is not called
Date Wed, 13 Jul 2016 17:29:20 GMT

    [ https://issues.apache.org/jira/browse/HIVE-14187?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15375396#comment-15375396
] 

Vaibhav Gumashta commented on HIVE-14187:
-----------------------------------------

[~mohitsabharwal] Thanks for the details. Makes sense, I'm +1 on the patch (might need rebase
for QA run).

> JDOPersistenceManager objects remain cached if MetaStoreClient#close is not called
> ----------------------------------------------------------------------------------
>
>                 Key: HIVE-14187
>                 URL: https://issues.apache.org/jira/browse/HIVE-14187
>             Project: Hive
>          Issue Type: Bug
>            Reporter: Mohit Sabharwal
>            Assignee: Mohit Sabharwal
>         Attachments: HIVE-14187.patch, HIVE-14187.patch
>
>
> JDOPersistenceManager objects are cached in JDOPersistenceManagerFactory by DataNuclues.
> A new JDOPersistenceManager object gets created for every HMS thread since ObjectStore
is a thread local.
> In non-embedded metastore mode, JDOPersistenceManager associated with a thread only gets
cleaned up if IMetaStoreClient#close is called by the client (which calls ObjectStore#shutdown
which calls JDOPersistenceManager#close which in turn removes the object from cache in JDOPersistenceManagerFactory#releasePersistenceManager
> https://github.com/datanucleus/datanucleus-api-jdo/blob/master/src/main/java/org/datanucleus/api/jdo/JDOPersistenceManagerFactory.java#L1271),
i.e. the object will remain cached if client does not call close.
> For example: If one interrupts out of hive CLI shell (instead of using 'exit;' command),
SessionState#close does not get called, and hence IMetaStoreClient#close does not get called.
> Instead of relying the client to call close, it's cleaner to automatically perform RawStore
related cleanup at the server end via deleteContext() which gets called when the server detects
a lost/closed connection.



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