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From "Anoop Sam John (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-15180) Reduce garbage created while reading Cells from Codec Decoder
Date Tue, 16 Feb 2016 07:36:18 GMT

    [ https://issues.apache.org/jira/browse/HBASE-15180?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15148203#comment-15148203
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Anoop Sam John commented on HBASE-15180:
----------------------------------------

Thanks for checking the test.. I will check that..
bq. UT case TestTag is in the hbase-server module which depends on hbase-common, but all changes
in the latest patch lie in hbase-common, and it seems Yetus only checked UT of the hbase-common
module and neglected the failure.
We need to make sure we run all test in all modules?  Because our tests are not really UTs.
 Some are (mainly those in hbase-server module) are FTs. So change in hbase-common can cause
issues with tests in hbase-server

> Reduce garbage created while reading Cells from Codec Decoder
> -------------------------------------------------------------
>
>                 Key: HBASE-15180
>                 URL: https://issues.apache.org/jira/browse/HBASE-15180
>             Project: HBase
>          Issue Type: Sub-task
>          Components: regionserver
>    Affects Versions: 0.98.0
>            Reporter: Anoop Sam John
>            Assignee: Anoop Sam John
>             Fix For: 2.0.0, 1.3.0, 1.2.1
>
>         Attachments: HBASE-15180.patch, HBASE-15180_V2.patch, HBASE-15180_V4.patch
>
>
> In KeyValueDecoder#parseCell (Default Codec decoder) we use KeyValueUtil#iscreate to
read cells from the InputStream. Here we 1st create a byte[] of length 4 and read the cell
length and then an array of Cell's length and read in cell bytes into it and create a KV.
> Actually in server we read the reqs into a byte[] and CellScanner is created on top of
a ByteArrayInputStream on top of this. By default in write path, we have MSLAB usage ON. So
while adding Cells to memstore, we will copy the Cell bytes to MSLAB memory chunks (default
2 MB size) and recreate Cells over that bytes.  So there is no issue if we create Cells over
the RPC read byte[] directly here in Decoder.  No need for 2 byte[] creation and copy for
every Cell in request.
> My plan is to make a Cell aware ByteArrayInputStream which can read Cells directly from
it.  
> Same Codec path is used in client side also. There better we can avoid this direct Cell
create and continue to do the copy to smaller byte[]s path.  Plan to introduce some thing
like a CodecContext associated with every Codec instance which can say the server/client context.



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