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From "Nicolas Liochon (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HBASE-11492) The servers do not honor the tcpNoDelay option
Date Fri, 11 Jul 2014 16:26:06 GMT

     [ https://issues.apache.org/jira/browse/HBASE-11492?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Nicolas Liochon updated HBASE-11492:
------------------------------------

    Fix Version/s:     (was: 0.94.22)

> The servers do not honor the tcpNoDelay option
> ----------------------------------------------
>
>                 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, 0.98.5
>
>         Attachments: 11492.v1.patch, 11492.v1.withp1.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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