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