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From "stack (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-15180) Reduce garbage created while reading Cells from Codec Decoder
Date Wed, 09 Mar 2016 06:48:41 GMT

    [ https://issues.apache.org/jira/browse/HBASE-15180?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15186625#comment-15186625
] 

stack commented on HBASE-15180:
-------------------------------

The horrid names are fine by me. They are explicit and for internal use only. Otherwise patch
looks good. Have you looked at moving what is common in IPCUtil up into hbase-common and then
shutting down the access on IPCUtil  so only accessible by ipc client? Can move its guts to
some codec util up in hbase common and the server-side could use that. Is that a load of work?
Is it doable? Ok to file a separate issue to do this.

> 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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