hbase-issues mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Yu Li (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-16205) When Cells are not copied to MSLAB, deep clone it while adding to Memstore
Date Thu, 14 Jul 2016 07:16:20 GMT

    [ https://issues.apache.org/jira/browse/HBASE-16205?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15376465#comment-15376465
] 

Yu Li commented on HBASE-16205:
-------------------------------

Nice catch [~anoop.hbase]!

Some suggestions:
1. Should we try to avoid the deep copy when not using MSLAB, in which case maybe directly
using the backend ByteBuffer has the same effect? Something like:
{code}
    if (getMemStoreLAB() != null && !useMSLAB) {
      cell = CellUtil.deepCopy(cell);
    }
{code}

2. Is it possible to avoid the deep copy when the backend ByteBuffer only contains a single
cell larger than {{maxAlloc}} size?

> 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.



--
This message was sent by Atlassian JIRA
(v6.3.4#6332)

Mime
View raw message