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https://issues.apache.org/jira/browse/HADOOP-2095?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12592530#action_12592530
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Arun C Murthy commented on HADOOP-2095:
---------------------------------------
+1 for Eric's proposal.
A minor refinement to discuss:
3) If ram is not full
c) initiate the merge with the in-memory compressed files which fit the quota;
continue downloading the compressed splits and stuff the compressed split as-is
in the InMemoryFileSystem (on ram).
The next pass of the merge will pick it up and run with it. It has the
advantage of saving ram and keeping the merge-code simple: each split is either
compressed (compression enabled) or not (compression disabled).
Thoughts?
> Reducer failed due to Out ofMemory
> ----------------------------------
>
> Key: HADOOP-2095
> URL: https://issues.apache.org/jira/browse/HADOOP-2095
> Project: Hadoop Core
> Issue Type: Bug
> Components: mapred
> Affects Versions: 0.15.0
> Reporter: Runping Qi
> Assignee: Arun C Murthy
> Attachments: HADOOP-2095_CompressedBytesWithCodecPool.patch,
> HADOOP-2095_debug.patch
>
>
> One of the reducers of my job failed with the following exceptions.
> The failure caused the whole job fail eventually.
> Java heapsize was 768MB and sort.io.mb was 140.
> 2007-10-23 19:24:06,100 WARN org.apache.hadoop.mapred.ReduceTask:
> task_200710231912_0001_r_000020_2 Intermediate Merge of the inmemory files
> threw an exception: java.lang.OutOfMemoryError: Java heap space
> at
> org.apache.hadoop.io.compress.DecompressorStream.(DecompressorStream.java:43)
> at
> org.apache.hadoop.io.compress.DefaultCodec.createInputStream(DefaultCodec.java:71)
> at org.apache.hadoop.io.SequenceFile$Reader.init(SequenceFile.java:1345)
> at org.apache.hadoop.io.SequenceFile$Reader.(SequenceFile.java:1231)
> at org.apache.hadoop.io.SequenceFile$Reader.(SequenceFile.java:1154)
> at
> org.apache.hadoop.io.SequenceFile$Sorter$SegmentDescriptor.nextRawKey(SequenceFile.java:2726)
> at
> org.apache.hadoop.io.SequenceFile$Sorter$MergeQueue.merge(SequenceFile.java:2543)
> at
> org.apache.hadoop.io.SequenceFile$Sorter.merge(SequenceFile.java:2297)
> at
> org.apache.hadoop.mapred.ReduceTask$ReduceCopier$InMemFSMergeThread.run(ReduceTask.java:1311)
> 2007-10-23 19:24:06,102 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200710231912_0001_r_000020_2 done copying
> task_200710231912_0001_m_001428_0 output .
> 2007-10-23 19:24:06,185 INFO org.apache.hadoop.fs.FileSystem: Initialized
> InMemoryFileSystem:
> ramfs://mapoutput31952838/task_200710231912_0001_r_000020_2/map_1423.out-0 of
> size (in bytes): 209715200
> 2007-10-23 19:24:06,193 ERROR org.apache.hadoop.mapred.ReduceTask: Map output
> copy failure: java.lang.NullPointerException
> at
> org.apache.hadoop.fs.InMemoryFileSystem$RawInMemoryFileSystem$FileAttributes.access$300(InMemoryFileSystem.java:366)
> at
> org.apache.hadoop.fs.InMemoryFileSystem$RawInMemoryFileSystem$InMemoryFileStatus.(InMemoryFileSystem.java:378)
> at
> org.apache.hadoop.fs.InMemoryFileSystem$RawInMemoryFileSystem.getFileStatus(InMemoryFileSystem.java:283)
> at
> org.apache.hadoop.fs.FilterFileSystem.getFileStatus(FilterFileSystem.java:251)
> at org.apache.hadoop.fs.FileSystem.getLength(FileSystem.java:449)
> at
> org.apache.hadoop.mapred.ReduceTask$ReduceCopier$MapOutputCopier.copyOutput(ReduceTask.java:738)
> at
> org.apache.hadoop.mapred.ReduceTask$ReduceCopier$MapOutputCopier.run(ReduceTask.java:665)
> 2007-10-23 19:24:06,193 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200710231912_0001_r_000020_2 Copying task_200710231912_0001_m_001215_0
> output from xxx
> 2007-10-23 19:24:06,188 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200710231912_0001_r_000020_2 Copying task_200710231912_0001_m_001211_0
> output from xxx
> 2007-10-23 19:24:06,185 ERROR org.apache.hadoop.mapred.ReduceTask: Map output
> copy failure: java.lang.NullPointerException
> at
> org.apache.hadoop.fs.InMemoryFileSystem$RawInMemoryFileSystem$InMemoryOutputStream.close(InMemoryFileSystem.java:161)
> at
> org.apache.hadoop.fs.FSDataOutputStream$PositionCache.close(FSDataOutputStream.java:49)
> at
> org.apache.hadoop.fs.FSDataOutputStream.close(FSDataOutputStream.java:64)
> at
> org.apache.hadoop.fs.ChecksumFileSystem$ChecksumFSOutputSummer.close(ChecksumFileSystem.java:312)
> at
> org.apache.hadoop.fs.FSDataOutputStream$PositionCache.close(FSDataOutputStream.java:49)
> at
> org.apache.hadoop.fs.FSDataOutputStream.close(FSDataOutputStream.java:64)
> at
> org.apache.hadoop.mapred.MapOutputLocation.getFile(MapOutputLocation.java:253)
> at
> org.apache.hadoop.mapred.ReduceTask$ReduceCopier$MapOutputCopier.copyOutput(ReduceTask.java:713)
> at
> org.apache.hadoop.mapred.ReduceTask$ReduceCopier$MapOutputCopier.run(ReduceTask.java:665)
> 2007-10-23 19:24:06,199 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200710231912_0001_r_000020_2 Copying task_200710231912_0001_m_001247_0
> output from .
> 2007-10-23 19:24:06,200 ERROR org.apache.hadoop.mapred.ReduceTask: Map output
> copy failure: java.lang.NullPointerException
> at
> org.apache.hadoop.fs.InMemoryFileSystem$RawInMemoryFileSystem$FileAttributes.access$300(InMemoryFileSystem.java:366)
> at
> org.apache.hadoop.fs.InMemoryFileSystem$RawInMemoryFileSystem$InMemoryFileStatus.(InMemoryFileSystem.java:378)
> at
> org.apache.hadoop.fs.InMemoryFileSystem$RawInMemoryFileSystem.getFileStatus(InMemoryFileSystem.java:283)
> at
> org.apache.hadoop.fs.FilterFileSystem.getFileStatus(FilterFileSystem.java:251)
> at org.apache.hadoop.fs.FileSystem.getLength(FileSystem.java:449)
> at
> org.apache.hadoop.mapred.ReduceTask$ReduceCopier$MapOutputCopier.copyOutput(ReduceTask.java:738)
> at
> org.apache.hadoop.mapred.ReduceTask$ReduceCopier$MapOutputCopier.run(ReduceTask.java:665)
> 2007-10-23 19:24:06,204 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200710231912_0001_r_000020_2 Copying task_200710231912_0001_m_001422_0
> output from .
> 2007-10-23 19:24:06,207 ERROR org.apache.hadoop.mapred.ReduceTask: Map output
> copy failure: java.lang.NullPointerException
> at
> org.apache.hadoop.fs.InMemoryFileSystem$RawInMemoryFileSystem$FileAttributes.access$300(InMemoryFileSystem.java:366)
> at
> org.apache.hadoop.fs.InMemoryFileSystem$RawInMemoryFileSystem$InMemoryFileStatus.(InMemoryFileSystem.java:378)
> at
> org.apache.hadoop.fs.InMemoryFileSystem$RawInMemoryFileSystem.getFileStatus(InMemoryFileSystem.java:283)
> at
> org.apache.hadoop.fs.FilterFileSystem.getFileStatus(FilterFileSystem.java:251)
> at org.apache.hadoop.fs.FileSystem.getLength(FileSystem.java:449)
> at
> org.apache.hadoop.mapred.ReduceTask$ReduceCopier$MapOutputCopier.copyOutput(ReduceTask.java:738)
> at
> org.apache.hadoop.mapred.ReduceTask$ReduceCopier$MapOutputCopier.run(ReduceTask.java:665)
> 2007-10-23 19:24:06,209 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200710231912_0001_r_000020_2 Copying task_200710231912_0001_m_001278_0
> output from .
> 2007-10-23 19:24:06,198 WARN org.apache.hadoop.mapred.TaskTracker: Error
> running child
> java.io.IOException: task_200710231912_0001_r_000020_2The reduce copier failed
> at org.apache.hadoop.mapred.ReduceTask.run(ReduceTask.java:253)
> at
> org.apache.hadoop.mapred.TaskTracker$Child.main(TaskTracker.java:1760)
> 2007-10-23 19:24:06,198 ERROR org.apache.hadoop.mapred.ReduceTask: Map output
> copy failure: java.lang.NullPointerException
> at
> org.apache.hadoop.fs.InMemoryFileSystem$RawInMemoryFileSystem$FileAttributes.access$300(InMemoryFileSystem.java:366)
> at
> org.apache.hadoop.fs.InMemoryFileSystem$RawInMemoryFileSystem$InMemoryFileStatus.(InMemoryFileSystem.java:378)
> at
> org.apache.hadoop.fs.InMemoryFileSystem$RawInMemoryFileSystem.getFileStatus(InMemoryFileSystem.java:283)
> at
> org.apache.hadoop.fs.FilterFileSystem.getFileStatus(FilterFileSystem.java:251)
> at org.apache.hadoop.fs.FileSystem.getLength(FileSystem.java:449)
> at
> org.apache.hadoop.mapred.ReduceTask$ReduceCopier$MapOutputCopier.copyOutput(ReduceTask.java:738)
> at
> org.apache.hadoop.mapred.ReduceTask$ReduceCopier$MapOutputCopier.run(ReduceTask.java:665)
> 2007-10-23 19:24:06,231 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200710231912_0001_r_000020_2 Copying task_200710231912_0001_m_001531_0
> output from .
> 2007-10-23 19:24:06,197 ERROR org.apache.hadoop.mapred.ReduceTask: Map output
> copy failure: java.lang.NullPointerException
> at
> org.apache.hadoop.fs.InMemoryFileSystem$RawInMemoryFileSystem$FileAttributes.access$300(InMemoryFileSystem.java:366)
> at
> org.apache.hadoop.fs.InMemoryFileSystem$RawInMemoryFileSystem$InMemoryFileStatus.(InMemoryFileSystem.java:378)
> at
> org.apache.hadoop.fs.InMemoryFileSystem$RawInMemoryFileSystem.getFileStatus(InMemoryFileSystem.java:283)
> at
> org.apache.hadoop.fs.FilterFileSystem.getFileStatus(FilterFileSystem.java:251)
> at org.apache.hadoop.fs.FileSystem.getLength(FileSystem.java:449)
> at
> org.apache.hadoop.mapred.ReduceTask$ReduceCopier$MapOutputCopier.copyOutput(ReduceTask.java:738)
> at
> org.apache.hadoop.mapred.ReduceTask$ReduceCopier$MapOutputCopier.run(ReduceTask.java:665)
> 2007-10-23 19:24:06,237 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200710231912_0001_r_000020_2 Copying task_200710231912_0001_m_001227_0
> output from .
> 2007-10-23 19:24:06,196 ERROR org.apache.hadoop.mapred.ReduceTask: Map output
> copy failure: java.lang.NullPointerException
> at
> org.apache.hadoop.fs.InMemoryFileSystem$RawInMemoryFileSystem$FileAttributes.access$300(InMemoryFileSystem.java:366)
> at
> org.apache.hadoop.fs.InMemoryFileSystem$RawInMemoryFileSystem$InMemoryFileStatus.(InMemoryFileSystem.java:378)
> at
> org.apache.hadoop.fs.InMemoryFileSystem$RawInMemoryFileSystem.getFileStatus(InMemoryFileSystem.java:283)
> at
> org.apache.hadoop.fs.FilterFileSystem.getFileStatus(FilterFileSystem.java:251)
> at org.apache.hadoop.fs.FileSystem.getLength(FileSystem.java:449)
> at
> org.apache.hadoop.mapred.ReduceTask$ReduceCopier$MapOutputCopier.copyOutput(ReduceTask.java:738)
> at
> org.apache.hadoop.mapred.ReduceTask$ReduceCopier$MapOutputCopier.run(ReduceTask.java:665)
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