[jira] [Commented] (HBASE-16205) When Cells are not copied to MSLAB, deep clone it while adding to Memstore

["binlijin (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HBASE-16205?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15376383#comment-15376383 ] 

binlijin commented on HBASE-16205:
----------------------------------

If the backend byte[] is bigger enough, all cells do not copy to the MSLAB.  
So what is the benefits of deep clone the big cell?


> When Cells are not copied to MSLAB, deep clone it while adding to Memstore
> --------------------------------------------------------------------------
>
>                 Key: HBASE-16205
>                 URL: https://issues.apache.org/jira/browse/HBASE-16205
>             Project: HBase
>          Issue Type: Sub-task
>          Components: regionserver
>    Affects Versions: 2.0.0
>            Reporter: Anoop Sam John
>            Assignee: Anoop Sam John
>            Priority: Critical
>             Fix For: 2.0.0
>
>         Attachments: HBASE-16205.patch
>
>
> This is imp after HBASE-15180 optimization. After that we the cells flowing in write path will be backed by the same byte[] where the RPC read the request into. By default we have MSLAB On and so we have a copy operation while adding Cells to memstore.  This copy might not be there if
> 1. MSLAB is turned OFF
> 2. Cell size is more than a configurable max size. This defaults to 256 KB
> 3. If the operation is Append/Increment. 
> In such cases, we should just clone the Cell into a new byte[] and then add to memstore.  Or else we keep referring to the bigger byte[] chunk for longer time.



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