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https://issues.apache.org/jira/browse/HADOOP-9640?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13849674#comment-13849674
 ] 

Hadoop QA commented on HADOOP-9640:
-----------------------------------

{color:green}+1 overall{color}.  Here are the results of testing the latest 
attachment 
  http://issues.apache.org/jira/secure/attachment/12618954/faircallqueue6.patch
  against trunk revision .

    {color:green}+1 @author{color}.  The patch does not contain any @author 
tags.

    {color:green}+1 tests included{color}.  The patch appears to include 4 new 
or modified test files.

    {color:green}+1 javac{color}.  The applied patch does not increase the 
total number of javac compiler warnings.

    {color:green}+1 javadoc{color}.  The javadoc tool did not generate any 
warning messages.

    {color:green}+1 eclipse:eclipse{color}.  The patch built with 
eclipse:eclipse.

    {color:green}+1 findbugs{color}.  The patch does not introduce any new 
Findbugs (version 1.3.9) warnings.

    {color:green}+1 release audit{color}.  The applied patch does not increase 
the total number of release audit warnings.

    {color:green}+1 core tests{color}.  The patch passed unit tests in 
hadoop-common-project/hadoop-common.

    {color:green}+1 contrib tests{color}.  The patch passed contrib unit tests.

Test results: 
https://builds.apache.org/job/PreCommit-HADOOP-Build/3361//testReport/
Console output: 
https://builds.apache.org/job/PreCommit-HADOOP-Build/3361//console

This message is automatically generated.

> RPC Congestion Control with FairCallQueue
> -----------------------------------------
>
>                 Key: HADOOP-9640
>                 URL: https://issues.apache.org/jira/browse/HADOOP-9640
>             Project: Hadoop Common
>          Issue Type: Improvement
>    Affects Versions: 3.0.0, 2.2.0
>            Reporter: Xiaobo Peng
>              Labels: hdfs, qos, rpc
>         Attachments: MinorityMajorityPerformance.pdf, 
> NN-denial-of-service-updated-plan.pdf, faircallqueue.patch, 
> faircallqueue2.patch, faircallqueue3.patch, faircallqueue4.patch, 
> faircallqueue5.patch, faircallqueue6.patch, 
> rpc-congestion-control-draft-plan.pdf
>
>
> Several production Hadoop cluster incidents occurred where the Namenode was 
> overloaded and failed to respond. 
> We can improve quality of service for users during namenode peak loads by 
> replacing the FIFO call queue with a [Fair Call 
> Queue|https://issues.apache.org/jira/secure/attachment/12616864/NN-denial-of-service-updated-plan.pdf].
>  (this plan supersedes rpc-congestion-control-draft-plan).
> Excerpted from the communication of one incident, “The map task of a user was 
> creating huge number of small files in the user directory. Due to the heavy 
> load on NN, the JT also was unable to communicate with NN...The cluster 
> became responsive only once the job was killed.”
> Excerpted from the communication of another incident, “Namenode was 
> overloaded by GetBlockLocation requests (Correction: should be getFileInfo 
> requests. the job had a bug that called getFileInfo for a nonexistent file in 
> an endless loop). All other requests to namenode were also affected by this 
> and hence all jobs slowed down. Cluster almost came to a grinding 
> halt…Eventually killed jobtracker to kill all jobs that are running.”
> Excerpted from HDFS-945, “We've seen defective applications cause havoc on 
> the NameNode, for e.g. by doing 100k+ 'listStatus' on very large directories 
> (60k files) etc.”



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