hbase-issues mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Lars Hofhansl (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-11492) The servers do not honor the tcpNoDelay option
Date Fri, 11 Jul 2014 17:28:08 GMT

    [ https://issues.apache.org/jira/browse/HBASE-11492?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14059046#comment-14059046
] 

Lars Hofhansl commented on HBASE-11492:
---------------------------------------

Does it make that much sense to set this true in HBase but not HDFS anyway? It means the we
avoid Nagle's with client RPCs but get delays when accessing HDFS from the HBase daemons.
Another option might be a prominent warning in the HBase log to also disable Nagle's for HDFS...?


> 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.



--
This message was sent by Atlassian JIRA
(v6.2#6252)

Mime
View raw message