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From "Hadoop QA (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HADOOP-9956) RPC listener inefficiently assigns connections to readers
Date Mon, 11 Nov 2013 21:34:19 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-9956?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13819428#comment-13819428
] 

Hadoop QA commented on HADOOP-9956:
-----------------------------------

{color:red}-1 overall{color}.  Here are the results of testing the latest attachment 
  http://issues.apache.org/jira/secure/attachment/12613227/HADOOP-9956.branch-23.patch
  against trunk revision .

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

Console output: https://builds.apache.org/job/PreCommit-HADOOP-Build/3273//console

This message is automatically generated.

> RPC listener inefficiently assigns connections to readers
> ---------------------------------------------------------
>
>                 Key: HADOOP-9956
>                 URL: https://issues.apache.org/jira/browse/HADOOP-9956
>             Project: Hadoop Common
>          Issue Type: Sub-task
>          Components: ipc
>    Affects Versions: 2.0.0-alpha, 3.0.0
>            Reporter: Daryn Sharp
>            Assignee: Daryn Sharp
>         Attachments: HADOOP-9956.branch-23.patch, HADOOP-9956.patch, HADOOP-9956.patch
>
>
> The socket listener and readers use a complex synchronization to update the reader's
NIO {{Selector}}.  Updating active selectors is not thread-safe so precautions are required.
> However, the current locking choreography results in a serialized distribution of new
connections to the parallel socket readers.  A slower/busier reader can stall the listener
and throttle performance.
> The problem manifests as unexpectedly low cpu utilization by the listener and readers
(~20-30%) under heavy load.  The call queue is shallow when it should be overflowing.



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