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From "Hudson (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (MAPREDUCE-5649) Reduce cannot use more than 2G memory for the final merge
Date Tue, 05 May 2015 15:15:06 GMT

    [ https://issues.apache.org/jira/browse/MAPREDUCE-5649?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14528615#comment-14528615
] 

Hudson commented on MAPREDUCE-5649:
-----------------------------------

SUCCESS: Integrated in Hadoop-Mapreduce-trunk-Java8 #185 (See [https://builds.apache.org/job/Hadoop-Mapreduce-trunk-Java8/185/])
MAPREDUCE-5649. Reduce cannot use more than 2G memory for the final merge. Contributed by
Gera Shegalov (jlowe: rev 7dc3c1203d1ab14c09d0aaf0869a5bcdfafb0a5a)
* hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/test/java/org/apache/hadoop/mapreduce/task/reduce/TestMergeManager.java
* hadoop-mapreduce-project/CHANGES.txt
* hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/task/reduce/MergeManagerImpl.java


> Reduce cannot use more than 2G memory  for the final merge
> ----------------------------------------------------------
>
>                 Key: MAPREDUCE-5649
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-5649
>             Project: Hadoop Map/Reduce
>          Issue Type: Bug
>          Components: mrv2
>            Reporter: stanley shi
>            Assignee: Gera Shegalov
>             Fix For: 2.8.0
>
>         Attachments: MAPREDUCE-5649.001.patch, MAPREDUCE-5649.002.patch, MAPREDUCE-5649.003.patch
>
>
> In the org.apache.hadoop.mapreduce.task.reduce.MergeManagerImpl.java file, in the finalMerge
method: 
>  int maxInMemReduce = (int)Math.min(
>         Runtime.getRuntime().maxMemory() * maxRedPer, Integer.MAX_VALUE);
>  
> This means no matter how much memory user has, reducer will not retain more than 2G data
in memory before the reduce phase starts.



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