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https://issues.apache.org/jira/browse/HBASE-2027?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Dave Latham updated HBASE-2027:
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Attachment: 2027-branch.20.patch
Here's a patch for 0.20 that changes the WeakHashMap to use WeakReference's to
the TableServers for values and adds an equals method to HBaseConfiguration so
that identical configs will share the same TableServers instead of each getting
their own. Also corrects the javadoc for HBaseConfiguration.hashCode().
> HConnectionManager.HBASE_INSTANCES leaks TableServers
> -----------------------------------------------------
>
> Key: HBASE-2027
> URL: https://issues.apache.org/jira/browse/HBASE-2027
> Project: Hadoop HBase
> Issue Type: Bug
> Affects Versions: 0.20.0
> Reporter: Dave Latham
> Assignee: Dave Latham
> Fix For: 0.20.3, 0.21.0
>
> Attachments: 2027-branch.20.patch
>
>
> HConnectionManager.HBASE_INSTANCES is a WeakHashMap from HBaseConfiguration
> to TableServers. However, each TableServers has a strong reference back to
> the HBaseConfiguration key so they are never freed. (See note at
> http://java.sun.com/javase/6/docs/api/java/util/WeakHashMap.html :
> "Implementation note: The value objects in a WeakHashMap are held by ordinary
> strong references. Thus care should be taken to ensure that value objects do
> not strongly refer to their own keys, either directly or indirectly, since
> that will prevent the keys from being discarded.")
> Moreover, HBaseConfiguration implements hashCode() but not equals() so
> identical HBaseConfiguration objects each get their own TableServers object.
> We had a long running HBase client process that was creating new HTable()
> objects, each creating a new HBaseConfiguration() and thus a new TableServers
> object. It eventually went OOM, and gave a heap dump indicating 360 MB of
> data retained by HBASE_INSTANCES.
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