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From "Nicolas Liochon (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HBASE-11492) The servers do not honnor the tcpNoDelay option
Date Thu, 10 Jul 2014 18:22:05 GMT

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

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

    Description: 
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.


  was:
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 divided by 5 when the connection is shared. This is the delayed ack kicking
in. This can be fixed by really using tcp no delay.




> The servers do not honnor the tcpNoDelay option
> -----------------------------------------------
>
>                 Key: HBASE-11492
>                 URL: https://issues.apache.org/jira/browse/HBASE-11492
>             Project: HBase
>          Issue Type: Bug
>          Components: regionserver
>    Affects Versions: 0.92.2, 0.98.0, 0.96.0, 0.99.0, 0.94.20
>            Reporter: Nicolas Liochon
>            Assignee: Nicolas Liochon
>            Priority: Critical
>             Fix For: 0.99.0, 0.98.5
>
>         Attachments: 11492.v1.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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