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https://issues.apache.org/jira/browse/HIVE-11499?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14949599#comment-14949599
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Thejas M Nair commented on HIVE-11499:
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+1
> 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
> 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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