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From "Nicolas Liochon (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-6295) Possible performance improvement in client batch operations: presplit and send in background
Date Mon, 15 Apr 2013 08:28:17 GMT

    [ https://issues.apache.org/jira/browse/HBASE-6295?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13631581#comment-13631581
] 

Nicolas Liochon commented on HBASE-6295:
----------------------------------------

I think we could simulate transient slowdown with a coprocessor. On a given RS, every 5 minutes,
the coprocessor does a sleep in the preput => during one minute; all puts takes 20ms than
they used to. In the client code, we just try to write randomly on all regions, with autoflush
off. The test should finish in both cases, but the number of puts written should be quite
different.

                
> Possible performance improvement in client batch operations: presplit and send in background
> --------------------------------------------------------------------------------------------
>
>                 Key: HBASE-6295
>                 URL: https://issues.apache.org/jira/browse/HBASE-6295
>             Project: HBase
>          Issue Type: Improvement
>          Components: Client, Performance
>    Affects Versions: 0.95.2
>            Reporter: Nicolas Liochon
>            Assignee: Nicolas Liochon
>              Labels: noob
>         Attachments: 6295.v1.patch, 6295.v2.patch, 6295.v3.patch
>
>
> today batch algo is:
> {noformat}
> for Operation o: List<Op>{
>   add o to todolist
>   if todolist > maxsize or o last in list
>     split todolist per location
>     send split lists to region servers
>     clear todolist
>     wait
> }
> {noformat}
> We could:
> - create immediately the final object instead of an intermediate array
> - split per location immediately
> - instead of sending when the list as a whole is full, send it when there is enough data
for a single location
> It would be:
> {noformat}
> for Operation o: List<Op>{
>   get location
>   add o to todo location.todolist
>   if (location.todolist > maxLocationSize)
>     send location.todolist to region server 
>     clear location.todolist
>     // don't wait, continue the loop
> }
> send remaining
> wait
> {noformat}
> It's not trivial to write if you add error management: retried list must be shared with
the operations added in the todolist. But it's doable.
> It's interesting mainly for 'big' writes

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