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From "deepankar (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-13819) Make RPC layer CellBlock buffer a DirectByteBuffer
Date Thu, 24 Mar 2016 04:38:25 GMT

    [ https://issues.apache.org/jira/browse/HBASE-13819?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15209736#comment-15209736
] 

deepankar commented on HBASE-13819:
-----------------------------------

bq. What you think of Anoop's idea of the BB being allocated onheap rather than offheap if
we can't get it from the pool? The allocation would be faster...


I feel both onheap / offheap allocation could suffer from the same problem as long as we are
not tight in the allocation (with less wastage compared to the anticipated response),  as
an example we somewhat made this error rare by increasing the MaxDirectMemory to a higher
value, but in the onheap case also if a user allocated his memory by tightly accounting stuff
he could may as well face the issue of unnecessary GCs I think. 


bq. deepankar Would you mind opening a new issue describing how you would like this to work?

created a jira HBASE-15525, we  would definitely help in whatever way we can on this.

> Make RPC layer CellBlock buffer a DirectByteBuffer
> --------------------------------------------------
>
>                 Key: HBASE-13819
>                 URL: https://issues.apache.org/jira/browse/HBASE-13819
>             Project: HBase
>          Issue Type: Sub-task
>          Components: Scanners
>            Reporter: Anoop Sam John
>            Assignee: Anoop Sam John
>             Fix For: 2.0.0, 1.3.0
>
>         Attachments: HBASE-13819.patch, HBASE-13819_branch-1.patch, HBASE-13819_branch-1.patch,
HBASE-13819_branch-1.patch, q.png
>
>
> In RPC layer, when we make a cellBlock to put as RPC payload, we will make an on heap
byte buffer (via BoundedByteBufferPool). The pool will keep upto certain number of buffers.
This jira aims at testing possibility for making this buffers off heap ones. (DBB)  The advantages
> 1. Unsafe based writes to off heap is faster than that to on heap. Now we are not using
unsafe based writes at all. Even if we add, DBB will be better
> 2. When Cells are backed by off heap (HBASE-11425) off heap to off heap writes will be
better
> 3. When checked the code in SocketChannel impl, if we pass a HeapByteBuffer to the socket
channel, it will create a temp DBB and copy data to there and only DBBs will be moved to Sockets.
If we make DBB 1st hand itself, we can  avoid this one more level of copying.
> Will do different perf testing with changed and report back.



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