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From "Eric Newton (JIRA)" <j...@apache.org>
Subject [jira] [Resolved] (ACCUMULO-599) investigate permgen collection and class unloading with concurrent mark and sweep garbage collector
Date Wed, 06 Aug 2014 20:22:12 GMT

     [ https://issues.apache.org/jira/browse/ACCUMULO-599?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Eric Newton resolved ACCUMULO-599.
----------------------------------

    Resolution: Not a Problem

This may be OBE.  In Java 7, the permgen is GC'd.  Of course, you have to have all your objects
deref'ed so classloaders can be removed. On larger nodes we do increase the size of the PermGen
with {{-XX:MaxPermSize=512m}}. 

> investigate permgen collection and class unloading with concurrent mark and sweep garbage
collector
> ---------------------------------------------------------------------------------------------------
>
>                 Key: ACCUMULO-599
>                 URL: https://issues.apache.org/jira/browse/ACCUMULO-599
>             Project: Accumulo
>          Issue Type: Bug
>          Components: scripts
>    Affects Versions: 1.3.6, 1.4.0
>            Reporter: Adam Fuchs
>            Assignee: Eric Newton
>
> The Java concurrent mark and sweep garbage collector appears to default to not unloading
classes or sweeping the permgen storage space. Accumulo reloads classes dynamically, potentially
contributing a lot to the permgen space. It is important that these classes be garbage collected
when we're done with them. Since we use -XX:+UseConcMarkSweepGC by default for all Accumulo
processes, should we also use -XX:+CMSClassUnloadingEnabled and -XX:+CMSPermGenSweepingEnabled?
Are there other flags or parameters that we should set to really do java garbage collection
properly in a long-lived instance?
> These should be set in conf/accumulo-env.sh as part of ACCUMULO_GENERAL_OPTS.



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