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https://issues.apache.org/jira/browse/YARN-2214?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14044952#comment-14044952
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Hadoop QA commented on YARN-2214:
---------------------------------
{color:red}-1 overall{color}. Here are the results of testing the latest
attachment
http://issues.apache.org/jira/secure/attachment/12652647/YARN-2214-v1.txt
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 1 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}. There were no new javadoc 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:red}-1 core tests{color}. The patch failed these unit tests in
hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager:
org.apache.hadoop.yarn.server.resourcemanager.ahs.TestRMApplicationHistoryWriter
{color:green}+1 contrib tests{color}. The patch passed contrib unit tests.
Test results:
https://builds.apache.org/job/PreCommit-YARN-Build/4095//testReport/
Console output: https://builds.apache.org/job/PreCommit-YARN-Build/4095//console
This message is automatically generated.
> preemptContainerPreCheck() in FSParentQueue delays convergence towards
> fairness
> -------------------------------------------------------------------------------
>
> Key: YARN-2214
> URL: https://issues.apache.org/jira/browse/YARN-2214
> Project: Hadoop YARN
> Issue Type: Bug
> Components: scheduler
> Affects Versions: 2.5.0
> Reporter: Ashwin Shankar
> Assignee: Ashwin Shankar
> Attachments: YARN-2214-v1.txt
>
>
> preemptContainerPreCheck() in FSParentQueue rejects preemption requests if
> the parent queue is below fair share. This can cause a delay in converging
> towards fairness when the starved leaf queue and the queue above fairshare
> belong under a non-root parent queue(ie their least common ancestor is a
> parent queue which is not root).
> Here is an example :
> root.parent has fair share = 80% and usage = 80%
> root.parent.child1 has fair share =40% usage = 80%
> root.parent.child2 has fair share=40% usage=0%
> Now a job is submitted to child2 and the demand is 40%.
> Preemption will kick in and try to reclaim all the 40% from child1.
> When it preempts the first container from child1,the usage of root.parent
> will become <80%, which is less than root.parent's fair share,causing
> preemption to stop.So only one container gets preempted in this round
> although the need is a lot more. child2 would eventually get to half its fair
> share but only after multiple rounds of preemption.
> Solution is to remove preemptContainerPreCheck() in FSParentQueue and keep it
> only in FSLeafQueue(which is already there).
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