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From "stack (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-15786) Create Offheap Memstore
Date Thu, 10 Nov 2016 06:12:58 GMT

    [ https://issues.apache.org/jira/browse/HBASE-15786?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15653155#comment-15653155
] 

stack commented on HBASE-15786:
-------------------------------

Ok. Yeah, update the subject.

Ok on MSLABImpl given it implements MemStoreLAB. Make sure you add to class comment that this
is going on (that mostly from pool but if not, can be offheap and onheap references...)

bq. ....this is for the Cells NOT of type ExtendedCell.. Actually speaking all cells in server
side is supposed to be ExtendedCell type any way. Still for the completion of the impl, we
consider other also.

Say this in code comments. This helps.

bq. This is existing ref. I did not add in this patch.

Makes sense. Came in for inmemory compaction.

bq. No. This tuner tune only Heap memory. 

Ok. Make clear in comments (if not already)

> Create Offheap Memstore
> -----------------------
>
>                 Key: HBASE-15786
>                 URL: https://issues.apache.org/jira/browse/HBASE-15786
>             Project: HBase
>          Issue Type: Sub-task
>          Components: regionserver
>            Reporter: ramkrishna.s.vasudevan
>            Assignee: Anoop Sam John
>             Fix For: 2.0.0
>
>         Attachments: HBASE-15786.patch
>
>
> We can make use of MSLAB pool for this off heap memstore. 
> Right now one can specify the global memstore size (heap size) as a % of max memory using
a config. We will add another config with which one can specify the global off heap memstore
size. This will be exact size not as %. When off heap memstore in use, we will give this entire
area for the MSLAB pool and that will create off heap chunks. So when cells are added to memstore,
the cell data gets copied into the off heap MSLAB chunk spaces. Note that when the pool size
is not really enough and we need additional chunk creation, we wont use off heap area for
that.  We dony want to create so many on demand DBBs.



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