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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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Status: Patch Available (was: Open)
> 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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