[jira] [Commented] (HIVE-11499) Datanucleus leaks classloaders when used using embedded metastore with HiveServer2 with UDFs

["Thejas M Nair (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HIVE-11499?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15012410#comment-15012410 ] 

Thejas M Nair commented on HIVE-11499:
--------------------------------------

Created HIVE-12458 to remove the jar from source.


> Datanucleus leaks classloaders when used using embedded metastore with HiveServer2 with UDFs
> --------------------------------------------------------------------------------------------
>
>                 Key: HIVE-11499
>                 URL: https://issues.apache.org/jira/browse/HIVE-11499
>             Project: Hive
>          Issue Type: Bug
>          Components: HiveServer2, Metastore
>    Affects Versions: 0.14.0, 1.0.0, 1.2.0, 1.1.0, 1.1.1, 1.2.1
>            Reporter: Vaibhav Gumashta
>            Assignee: Vaibhav Gumashta
>             Fix For: 1.3.0, 2.0.0
>
>         Attachments: HIVE-11499.1.patch, HIVE-11499.3.patch, HIVE-11499.4.patch, HS2-NucleusCache-Leak.tiff
>
>
> When UDFs are used, we create a new classloader to add the UDF jar. Similar to what hadoop's reflection utils does(HIVE-11408), datanucleus caches the classloaders (https://github.com/datanucleus/datanucleus-core/blob/3.2/src/java/org/datanucleus/NucleusContext.java#L161). JDOPersistanceManager factory (1 per JVM) holds on to a NucleusContext reference (https://github.com/datanucleus/datanucleus-api-jdo/blob/3.2/src/java/org/datanucleus/api/jdo/JDOPersistenceManagerFactory.java#L115). Until we call  NucleusContext#close, the classloader cache is not cleared. In case of UDFs this can lead to permgen leak, as shown in the attached screenshot, where NucleusContext holds on to several URLClassloader objects.



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