[jira] [Updated] (HBASE-4027) Enable direct byte buffers LruBlockCache

["Jean-Daniel Cryans (Updated) (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HBASE-4027?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Jean-Daniel Cryans updated HBASE-4027:
--------------------------------------

    Release Note: Setting -XX:MaxDirectMemorySize in hbase-env.sh enables this feature. The file already has a line you can uncomment and you need to set the size of the direct memory (your total memory - size allocated to memstores - size allocated to the normal block cache - some head room for the other functionalities).  (was: Allows the enabling off an off heap cache in hbase.  Set hbase.offheapcachesize in hbase-site.xml

Then, uncomment the line in hbase-env.sh. Cache does a slab allocation model similar to memcached.
)

I changed the release note, the patch doesn't have a "hbase.offheapcachesize" configuration and it's enabled as soon as you set -XX:MaxDirectMemorySize (which is actually a big problem when you consider this: http://hbase.apache.org/book.html#trouble.client.oome.directmemory.leak). I'm opening followup jiras.
                
> Enable direct byte buffers LruBlockCache
> ----------------------------------------
>
>                 Key: HBASE-4027
>                 URL: https://issues.apache.org/jira/browse/HBASE-4027
>             Project: HBase
>          Issue Type: Improvement
>            Reporter: Jason Rutherglen
>            Assignee: Li Pi
>            Priority: Minor
>             Fix For: 0.92.0
>
>         Attachments: 4027-v5.diff, 4027v7.diff, HBase-4027 (1).pdf, HBase-4027.pdf, HBase4027v8.diff, HBase4027v9.diff, hbase-4027-v10.5.diff, hbase-4027-v10.diff, hbase-4027v10.6.diff, hbase-4027v13.1.diff, hbase-4027v15.3.diff, hbase-4027v6.diff, hbase4027v11.5.diff, hbase4027v11.6.diff, hbase4027v11.7.diff, hbase4027v11.diff, hbase4027v12.1.diff, hbase4027v12.diff, hbase4027v15.2.diff, slabcachepatch.diff, slabcachepatchv2.diff, slabcachepatchv3.1.diff, slabcachepatchv3.2.diff, slabcachepatchv3.diff, slabcachepatchv4.5.diff, slabcachepatchv4.diff
>
>
> Java offers the creation of direct byte buffers which are allocated outside of the heap.
> They need to be manually free'd, which can be accomplished using an documented {{clean}} method.
> The feature will be optional.  After implementing, we can benchmark for differences in speed and garbage collection observances.

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