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From "Zephyr Guo (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-14490) [RpcServer] reuse request read buffer
Date Thu, 01 Oct 2015 11:12:27 GMT

    [ https://issues.apache.org/jira/browse/HBASE-14490?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14939688#comment-14939688
] 

Zephyr Guo commented on HBASE-14490:
------------------------------------

[~anoop.hbase] Thanks for your review.

{quote}
 If read alone is the consideration, it is high?
{quote}
Seem big.How about 16K?I have no test.Just experience...
Dynamic adjustment is better?Set it to average at sometime.
{quote}
We need to have check <= ?
{quote}
No.
If dataLength==READ_REQ_REUSED_BUF_SIZE, we can use it exactly.

{quote}
processRequest(ByteBuffer buf)
{quote}
I will improve the method.

{quote}
The 'unwrappedData' ref set to be null now. But we dont do that for data. That be an issue?
Why dont going with SoftRef way here? Am I missing some thing?
{quote}

invoking chain:
process —> saslReadAndProcess —> processUnwrappedData

Supposing we come into processUnwrappedData now.Define A as reused buffer and B as temporary
buffer(a large buffer).

{{data}} is not null obviously(reference to A or B) and it has no useful data to read.So we
just use {{data}} again.
 
In the end of {{process}}, we do {{data = null}}. If {{data}} is A, the BB will be reference
by SoftRef only.If data is B, no one reference to it.

Because we have no variable {{unwrappedData}}, so we can clear buffer uniformly.Just set data
to be null in end of {{process}}.

{quote}
U mean call to evaluateResponse occurs just once? After that the boolean saslContextEstablished
will be true.
{quote}
At least occur one time.I just want to say ‘evaluateResponse(byte[] rsp, int off, int len)
is best’.But SASL API not look like this currently.So we have to copy.
{code}
replyToken = saslServer.evaluateResponse(
            new Bytes(saslToken.array(), saslToken.position(), saslToken.remaining()).copyBytes());
{code}
I mark here by ’TODO’.If the API be improved in the future, we can modify here.If there
misunderstanding , can remove.It’s not important.


> [RpcServer] reuse request read buffer
> -------------------------------------
>
>                 Key: HBASE-14490
>                 URL: https://issues.apache.org/jira/browse/HBASE-14490
>             Project: HBase
>          Issue Type: Improvement
>          Components: IPC/RPC
>    Affects Versions: 2.0.0, 1.0.2
>            Reporter: Zephyr Guo
>            Assignee: Zephyr Guo
>              Labels: performance
>             Fix For: 2.0.0, 1.0.2
>
>         Attachments: HBASE-14490-v1.patch, HBASE-14490-v2.patch, HBASE-14490-v3.patch,
HBASE-14490-v4.patch, HBASE-14490-v5.patch, HBASE-14490-v6.patch, HBASE-14490-v7.patch, HBASE-14490-v8.patch,
HBASE-14490-v9.patch
>
>
> Reuse buffer to read request.It's not necessary free data's buffer for each request.Optimization
is to reduce the times that allocate ByteBuffer.
> *patch modification*
> * {{saslReadAndProcess}} and {{processOneRpc}} accept a ByteBuffer instead of byte[].
> * {{processUnwrappedData}} can reuse the same ByteBuffer that {{saslReadAndProcess}}
used.
> * Maintaining a reused ByteBuffer each {{Reader}} for most request.
> ** Buffer size is fixed.
> ** Using a SoftReference to reference the buffer.
> ** If request is too large, we allocate a temporary ByteBuffer.Freeing it when  {{process()}}
will have been finished.



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