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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 Wed, 09 Mar 2016 03:11:41 GMT

    [ https://issues.apache.org/jira/browse/HBASE-15180?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15186406#comment-15186406
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Anoop Sam John commented on HBASE-15180:
----------------------------------------

Ya to make sure the client uses only which it supposed to, we can rename method at least.
 Any better name suggestion boss [~saint.ack@gmail.com]?
The best way would have been that, the codec instance know where am I.  Whether it is in client
context or server.  We need to set it while constructing Codec instance.   But ya at least
a method name change we can do now.
I will fix ur suggestion abt explicit javadoc statement on commit.  Thanks for the review.
Once Stack also good abt the patch, will commit.

> 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
>
>         Attachments: HBASE-15180.patch, HBASE-15180_V2.patch, HBASE-15180_V4.patch, HBASE-15180_V6.patch,
HBASE-15180_V7.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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