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From "ramkrishna.s.vasudevan (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-17644) Always create ByteBufferCells after copying to MSLAB
Date Wed, 15 Feb 2017 06:34:41 GMT

    [ https://issues.apache.org/jira/browse/HBASE-17644?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15867336#comment-15867336
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ramkrishna.s.vasudevan commented on HBASE-17644:
------------------------------------------------

If that is the case then
{code}
 @Override
63	  public boolean hasArray() {
64	    return false;
65	  }
66	
67	  @Override
68	  public byte[] getValueArray() {
69	    throw new UnsupportedOperationException(
70	        "Tag is backed by an off heap buffer. Use getValueByteBuffer()");
71	  }
72	
{code}
this code inside ByteBufferTag should be changed. 

> Always create ByteBufferCells after copying to MSLAB
> ----------------------------------------------------
>
>                 Key: HBASE-17644
>                 URL: https://issues.apache.org/jira/browse/HBASE-17644
>             Project: HBase
>          Issue Type: Sub-task
>          Components: regionserver
>    Affects Versions: 2.0.0
>            Reporter: ramkrishna.s.vasudevan
>            Assignee: Anoop Sam John
>             Fix For: 2.0.0
>
>         Attachments: HBASE-17644.patch
>
>
> We create a cell out of the Bytebuffer that is returned by MSLAB. This BB can be offheap
or onheap type. If MSLAB is full we return onheap byte buffer. So the place where we create
a cell by copying data to this buffer we either create KeyValue or OffheapKV based on the
buffer type. So what we saw in tests is that since we have a combination of Cells the comparisons
that happens when adding to memstore happens millions of times and that has an impact on the
performance of write path. In read path this is not significant enougth (though we have plans
to just create one type of cells every where in Server side). 



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