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From "binlijin (JIRA)" <j...@apache.org>
Subject [jira] [Comment Edited] (HBASE-16205) When Cells are not copied to MSLAB, deep clone it while adding to Memstore
Date Thu, 14 Jul 2016 07:59:20 GMT

    [ https://issues.apache.org/jira/browse/HBASE-16205?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15376523#comment-15376523
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binlijin edited comment on HBASE-16205 at 7/14/16 7:59 AM:
-----------------------------------------------------------

[~anoop.hbase], sir
With MSLAB turn on. What i am suggest is:
One case: a request with two cell: cell1=100k, cell2=100k, cell1+cell2<256K so cell1 and
cell2 copy to MSLAB.
Two case: a request with two cell: cell1=200k, cell2=100k, cell1+cell2>256K, cell1 and
cell2 do not copy to MSLAB.
Three case: a request with two cell: cell1=300k, cell2=1k,  cell1>256K,  cell1 and cell2
do not copy to MSLAB.

And the two and three case is what i am suggested.




was (Author: aoxiang):
[~anoop.hbase], sir
With MSLAB turn on. What i am suggest is:
One case: a request with two cell: cell1=100k, cell2=100k, cell1+cell2<256K so cell1 and
cell2 copy to MSLAB.
Two case: a request with two cell: cell1=200k, cell2=100k, cell1+cell2>256K, cell1 and
cell2 do not copy to MSLAB.
Three case: a request with two cell: cell1=300k, cell2=1k,  cell2>256K,  cell1 and cell2
do not copy to MSLAB.

And the two and three case is what i am suggested.



> 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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