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Date: Fri, 11 Jul 2014 20:53:05 +0000 (UTC)
From: "Hadoop QA (JIRA)" <jira@apache.org>
To: issues@hbase.apache.org
Message-ID: <JIRA.12726604.1405006020298.27044.1405111985704@arcas>
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Subject: [jira] [Commented] (HBASE-11492) Hadoop configuration overrides
 some ipc parameters including tcpNoDelay
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    [ https://issues.apache.org/jira/browse/HBASE-11492?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14059337#comment-14059337 ] 

Hadoop QA commented on HBASE-11492:
-----------------------------------

{color:red}-1 overall{color}.  Here are the results of testing the latest attachment 
  http://issues.apache.org/jira/secure/attachment/12655294/11492.v2-0.98.patch
  against trunk revision .
  ATTACHMENT ID: 12655294

    {color:green}+1 @author{color}.  The patch does not contain any @author tags.

    {color:green}+1 tests included{color}.  The patch appears to include 8 new or modified tests.

    {color:red}-1 patch{color}.  The patch command could not apply the patch.

Console output: https://builds.apache.org/job/PreCommit-HBASE-Build/10039//console

This message is automatically generated.

> Hadoop configuration overrides some ipc parameters including tcpNoDelay
> -----------------------------------------------------------------------
>
>                 Key: HBASE-11492
>                 URL: https://issues.apache.org/jira/browse/HBASE-11492
>             Project: HBase
>          Issue Type: Bug
>          Components: regionserver
>    Affects Versions: 0.98.0, 0.99.0
>            Reporter: Nicolas Liochon
>            Assignee: Nicolas Liochon
>            Priority: Critical
>             Fix For: 0.99.0, 0.98.4
>
>         Attachments: 11492.v1.patch, 11492.v1.withp1.patch, 11492.v2-0.98.patch, 11492.v2.patch
>
>
> There is an option to set tcpNoDelay, defaulted to true, but the socket channel is actually not changed. As a consequence, the server works with nagle enabled. This leads to very degraded behavior when a single connection is shared between threads. We enter into conflicts with nagle and tcp delayed ack. 
> Here is an example of performance with the PE tool plus HBASE-11491:
> {noformat}
> oneCon     #client       sleep          exeTime (seconds)                             avg latency, sleep excluded (microseconds)
> true           1               0                31                                                     310
> false          1               0                31                                                     310
> true           2               0                50                                                      500
> false          2               0               31                                                      310
> true           2                5               488 (including 200s sleeping)               2880 
> false          2               5               246  (including 200s sleeping)               460
> {noformat}
> The latency is multiple by 5 (2880 vs 460) when the connection is shared. This is the delayed ack kicking in. This can be fixed by really using tcp no delay.
> Any application sharing the tcp connection between threads has the issue.


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