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https://issues.apache.org/jira/browse/MAPREDUCE-4228?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13269962#comment-13269962
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Hadoop QA commented on MAPREDUCE-4228:
--------------------------------------
-1 overall. Here are the results of testing the latest attachment
http://issues.apache.org/jira/secure/attachment/12525912/MAPREDUCE-4228.patch
against trunk revision .
+1 @author. The patch does not contain any @author tags.
+1 tests included. The patch appears to include 1 new or modified test
files.
-1 javadoc. The javadoc tool appears to have generated 2 warning messages.
+1 javac. The applied patch does not increase the total number of javac
compiler warnings.
+1 eclipse:eclipse. The patch built with eclipse:eclipse.
-1 findbugs. The patch appears to cause Findbugs (version 1.3.9) to fail.
+1 release audit. The applied patch does not increase the total number of
release audit warnings.
+1 core tests. The patch passed unit tests in
hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app.
+1 contrib tests. The patch passed contrib unit tests.
Test results:
https://builds.apache.org/job/PreCommit-MAPREDUCE-Build/2365//testReport/
Console output:
https://builds.apache.org/job/PreCommit-MAPREDUCE-Build/2365//console
This message is automatically generated.
> mapreduce.job.reduce.slowstart.completedmaps is not working properly to delay
> the scheduling of the reduce tasks
> ----------------------------------------------------------------------------------------------------------------
>
> Key: MAPREDUCE-4228
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-4228
> Project: Hadoop Map/Reduce
> Issue Type: Bug
> Components: applicationmaster, mrv2
> Affects Versions: 0.23.1
> Reporter: Jason Lowe
> Assignee: Jason Lowe
> Attachments: MAPREDUCE-4228.patch, MAPREDUCE-4228.patch
>
>
> If no more map tasks need to be scheduled but not all have completed, the
> ApplicationMaster will start scheduling reducers even if the number of
> completed maps has not met the mapreduce.job.reduce.slowstart.completedmaps
> threshold. For example, if the property is set to 1.0 all maps should
> complete before any reducers are scheduled. However the reducers are
> scheduled as soon as the last map task is assigned to a container. For a job
> with very long-running maps, a cluster with enough capacity to launch all map
> tasks could cause reducers to launch prematurely and waste cluster resources.
> Thanks to Phil Su for discovering this issue.
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