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https://issues.apache.org/jira/browse/MAPREDUCE-4733?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13480720#comment-13480720
 ] 

Hudson commented on MAPREDUCE-4733:
-----------------------------------

Integrated in Hadoop-Hdfs-0.23-Build #410 (See 
[https://builds.apache.org/job/Hadoop-Hdfs-0.23-Build/410/])
    MAPREDUCE-4733. Reducer can fail to make progress during shuffle if too 
many reducers complete consecutively. Contributed by Jason Lowe.
svn merge --ignore-ancestry -c 1400264 ../../trunk/ (Revision 1400267)

     Result = SUCCESS
vinodkv : 
http://svn.apache.org/viewcvs.cgi/?root=Apache-SVN&view=rev&rev=1400267
Files : 
* /hadoop/common/branches/branch-0.23/hadoop-mapreduce-project/CHANGES.txt
* 
/hadoop/common/branches/branch-0.23/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/main/java/org/apache/hadoop/mapred/TaskAttemptListenerImpl.java
* 
/hadoop/common/branches/branch-0.23/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/main/java/org/apache/hadoop/mapreduce/v2/app/job/Job.java
* 
/hadoop/common/branches/branch-0.23/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/main/java/org/apache/hadoop/mapreduce/v2/app/job/impl/JobImpl.java
* 
/hadoop/common/branches/branch-0.23/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/test/java/org/apache/hadoop/mapred/TestTaskAttemptListenerImpl.java
* 
/hadoop/common/branches/branch-0.23/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/test/java/org/apache/hadoop/mapreduce/v2/app/MockJobs.java
* 
/hadoop/common/branches/branch-0.23/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/test/java/org/apache/hadoop/mapreduce/v2/app/TestFetchFailure.java
* 
/hadoop/common/branches/branch-0.23/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/test/java/org/apache/hadoop/mapreduce/v2/app/TestRuntimeEstimators.java
* 
/hadoop/common/branches/branch-0.23/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-hs/src/main/java/org/apache/hadoop/mapreduce/v2/hs/CompletedJob.java
* 
/hadoop/common/branches/branch-0.23/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-hs/src/main/java/org/apache/hadoop/mapreduce/v2/hs/PartialJob.java
* 
/hadoop/common/branches/branch-0.23/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-hs/src/test/java/org/apache/hadoop/mapreduce/v2/hs/MockHistoryJobs.java

                
> Reducer can fail to make progress during shuffle if too many reducers 
> complete consecutively
> --------------------------------------------------------------------------------------------
>
>                 Key: MAPREDUCE-4733
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-4733
>             Project: Hadoop Map/Reduce
>          Issue Type: Bug
>          Components: applicationmaster, mrv2
>    Affects Versions: 0.23.3
>            Reporter: Jason Lowe
>            Assignee: Jason Lowe
>             Fix For: 2.0.3-alpha, 0.23.5
>
>         Attachments: MAPREDUCE-4733.patch, MAPREDUCE-4733.patch, 
> MAPREDUCE-4733.patch
>
>
> TaskAttemptListenerImpl implements getMapCompletionEvents by calling 
> Job.getTaskAttemptCompletionEvents with the same fromEvent and maxEvents 
> passed in from the reducer and then filtering the result for just map events. 
> We can't filter the task completion event list and expect the caller's 
> "window" into the list to match up.  As soon as a reducer event appears in 
> the list it means we are redundantly sending map completion events that were 
> already seen by the reducer.
> Worst case the reducer will hang if all of the events in the requested window 
> are reducer events.  In that case zero events will be reported back to the 
> caller and it won't bump up fromEvent on the next call.  Reducer then never 
> sees the final map completion events needed to complete the shuffle. This 
> could happen in a case where all maps complete, more than MAX_EVENTS reducers 
> complete consecutively, but some straggling reducers get fetch failures and 
> cause a map to be restarted.

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