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https://issues.apache.org/jira/browse/MAPREDUCE-5028?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13659666#comment-13659666
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Gopal V commented on MAPREDUCE-5028:
------------------------------------
[~kkambatl], I took some time to go through your patch.
Patch contains 2 different fixes, which deserve their own tests & commits.
Good catch on the overflow with the kvindex,kvend variables. That is a bug with
the mapper with large buffers. That is a good & clean fix.
But for the second issue, I found out it triggered when the inline Combiner is
run when there are > 3 spills in the SpillThread. This wasn't tested in
[~acmurthy]'s test-app (but the word-count sum combiner does trigger it
cleanly).
And there I found your fix to be suspect. So, for the sake of data I logged
every call to reset and crawled a 13 gb log file to find out offenders in reset
(i.e where (long)start + (long)length > input.length).
This particular back-trace stood out as a key offender. I found that to be
significant instead of merely locating the overflow cases.
{code}
org.apache.hadoop.mapred.MapTask$MapOutputBuffer$MRResultIterator.getKey(MapTask.java:1784)
org.apache.hadoop.mapreduce.task.ReduceContextImpl.nextKeyValue(ReduceContextImpl.java:138)
{code}
I will take a closer look at that code, it might be cleaner to tackle the issue
at the first-cause location.
> Maps fail when io.sort.mb is set to high value
> ----------------------------------------------
>
> Key: MAPREDUCE-5028
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-5028
> Project: Hadoop Map/Reduce
> Issue Type: Bug
> Affects Versions: 1.1.1, 2.0.3-alpha, 0.23.5
> Reporter: Karthik Kambatla
> Assignee: Karthik Kambatla
> Priority: Critical
> Fix For: 1.2.0, 2.0.5-beta
>
> Attachments: mr-5028-branch1.patch, mr-5028-branch1.patch,
> mr-5028-branch1.patch, MR-5028_testapp.patch, mr-5028-trunk.patch,
> mr-5028-trunk.patch, mr-5028-trunk.patch, repro-mr-5028.patch
>
>
> Verified the problem exists on branch-1 with the following configuration:
> Pseudo-dist mode: 2 maps/ 1 reduce, mapred.child.java.opts=-Xmx2048m,
> io.sort.mb=1280, dfs.block.size=2147483648
> Run teragen to generate 4 GB data
> Maps fail when you run wordcount on this configuration with the following
> error:
> {noformat}
> java.io.IOException: Spill failed
> at
> org.apache.hadoop.mapred.MapTask$MapOutputBuffer.collect(MapTask.java:1031)
> at
> org.apache.hadoop.mapred.MapTask$NewOutputCollector.write(MapTask.java:692)
> at
> org.apache.hadoop.mapreduce.TaskInputOutputContext.write(TaskInputOutputContext.java:80)
> at
> org.apache.hadoop.examples.WordCount$TokenizerMapper.map(WordCount.java:45)
> at
> org.apache.hadoop.examples.WordCount$TokenizerMapper.map(WordCount.java:34)
> at org.apache.hadoop.mapreduce.Mapper.run(Mapper.java:144)
> at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:766)
> at org.apache.hadoop.mapred.MapTask.run(MapTask.java:370)
> at org.apache.hadoop.mapred.Child$4.run(Child.java:255)
> at java.security.AccessController.doPrivileged(Native Method)
> at javax.security.auth.Subject.doAs(Subject.java:396)
> at
> org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1149)
> at org.apache.hadoop.mapred.Child.main(Child.java:249)
> Caused by: java.io.EOFException
> at java.io.DataInputStream.readInt(DataInputStream.java:375)
> at org.apache.hadoop.io.IntWritable.readFields(IntWritable.java:38)
> at
> org.apache.hadoop.io.serializer.WritableSerialization$WritableDeserializer.deserialize(WritableSerialization.java:67)
> at
> org.apache.hadoop.io.serializer.WritableSerialization$WritableDeserializer.deserialize(WritableSerialization.java:40)
> at
> org.apache.hadoop.mapreduce.ReduceContext.nextKeyValue(ReduceContext.java:116)
> at
> org.apache.hadoop.mapreduce.ReduceContext.nextKey(ReduceContext.java:92)
> at org.apache.hadoop.mapreduce.Reducer.run(Reducer.java:175)
> at
> org.apache.hadoop.mapred.Task$NewCombinerRunner.combine(Task.java:1505)
> at
> org.apache.hadoop.mapred.MapTask$MapOutputBuffer.sortAndSpill(MapTask.java:1438)
> at
> org.apache.hadoop.mapred.MapTask$MapOutputBuffer.access$1800(MapTask.java:855)
> at
> org.apache.hadoop.mapred.MapTask$MapOutputBuffer$SpillThread.run(MapTask.java:1346)
> {noformat}
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