[jira] [Commented] (HADOOP-8069) Enable TCP_NODELAY by default for IPC

["Daryn Sharp (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HADOOP-8069?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13717561#comment-13717561 ] 

Daryn Sharp commented on HADOOP-8069:
-------------------------------------

Should we again consider changing the default for nodelay?  On one of our busiest cluster, listStatus represents about ~3% of RPC load.  A few extra packets here and there on a fast network are going to be delivered much faster than the nagle delay. 
                
> Enable TCP_NODELAY by default for IPC
> -------------------------------------
>
>                 Key: HADOOP-8069
>                 URL: https://issues.apache.org/jira/browse/HADOOP-8069
>             Project: Hadoop Common
>          Issue Type: Improvement
>          Components: ipc
>    Affects Versions: 0.23.0
>            Reporter: Todd Lipcon
>            Assignee: Todd Lipcon
>         Attachments: hadoop-8069.txt
>
>
> I think we should switch the default for the IPC client and server NODELAY options to true. As wikipedia says:
> {quote}
> In general, since Nagle's algorithm is only a defense against careless applications, it will not benefit a carefully written application that takes proper care of buffering; the algorithm has either no effect, or negative effect on the application.
> {quote}
> Since our IPC layer is well contained and does its own buffering, we shouldn't be careless.

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