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https://issues.apache.org/jira/browse/MAPREDUCE-6447?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15270120#comment-15270120
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Prateek Rungta commented on MAPREDUCE-6447:
-------------------------------------------
for posterity, Jason Zhu does a pretty good job of root-causing this on his
blog - [1]
tl;dr -
{quote}
Consequently, the product of 'mapreduce.reduce.shuffle.input.buffer.percent'
multiplies by 'mapreduce.reduce.shuffle.parallelcopies' should not be greater
than 1, or, in the extreme case, OOM will be thrown provided all mappers
complete at the same time and all the outputs is in the manner of in-memory
shuffling.
But here's a compromise between OOM and throughput. The product can be greater
than 1 if some OOMs is tolerable.
{quote}
[1]:
http://jason4zhu.blogspot.com/2014/11/shuffle-error-by-java-lang-out-of-memory-error-java-heap-space.html
> reduce shuffle throws "java.lang.OutOfMemoryError: Java heap space"
> -------------------------------------------------------------------
>
> Key: MAPREDUCE-6447
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-6447
> Project: Hadoop Map/Reduce
> Issue Type: Bug
> Affects Versions: 2.5.0, 2.6.0, 2.5.1, 2.7.1
> Reporter: shuzhangyao
> Assignee: shuzhangyao
> Priority: Minor
>
> 2015-08-11 14:03:54,550 WARN [main] org.apache.hadoop.mapred.YarnChild:
> Exception running child :
> org.apache.hadoop.mapreduce.task.reduce.Shuffle$ShuffleError: error in
> shuffle in fetcher#10
> at org.apache.hadoop.mapreduce.task.reduce.Shuffle.run(Shuffle.java:134)
> at org.apache.hadoop.mapred.ReduceTask.run(ReduceTask.java:376)
> at org.apache.hadoop.mapred.YarnChild$2.run(YarnChild.java:168)
> at java.security.AccessController.doPrivileged(Native Method)
> at javax.security.auth.Subject.doAs(Subject.java:415)
> at
> org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1614)
> at org.apache.hadoop.mapred.YarnChild.main(YarnChild.java:163)
> Caused by: java.lang.OutOfMemoryError: Java heap space
> at
> org.apache.hadoop.io.BoundedByteArrayOutputStream.<init>(BoundedByteArrayOutputStream.java:56)
> at
> org.apache.hadoop.io.BoundedByteArrayOutputStream.<init>(BoundedByteArrayOutputStream.java:46)
> at
> org.apache.hadoop.mapreduce.task.reduce.InMemoryMapOutput.<init>(InMemoryMapOutput.java:63)
> at
> org.apache.hadoop.mapreduce.task.reduce.MergeManagerImpl.unconditionalReserve(MergeManagerImpl.java:303)
> at
> org.apache.hadoop.mapreduce.task.reduce.MergeManagerImpl.reserve(MergeManagerImpl.java:293)
> at
> org.apache.hadoop.mapreduce.task.reduce.Fetcher.copyMapOutput(Fetcher.java:511)
> at
> org.apache.hadoop.mapreduce.task.reduce.Fetcher.copyFromHost(Fetcher.java:329)
> at org.apache.hadoop.mapreduce.task.reduce.Fetcher.run(Fetcher.java:193)
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