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From "sam liu (JIRA)" <j...@apache.org>
Subject [jira] [Created] (MAPREDUCE-5506) Hadoop-1.1.1 occurs ArrayIndexOutOfBoundsException with MultithreadedMapRunner
Date Fri, 13 Sep 2013 07:41:51 GMT
sam liu created MAPREDUCE-5506:
----------------------------------

             Summary: Hadoop-1.1.1 occurs ArrayIndexOutOfBoundsException with MultithreadedMapRunner
                 Key: MAPREDUCE-5506
                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-5506
             Project: Hadoop Map/Reduce
          Issue Type: Bug
          Components: mrv1
    Affects Versions: 1.1.1
         Environment: RHEL 6.3 x86_64
            Reporter: sam liu
            Priority: Blocker


After I set:
- 'jobConf.setMapRunnerClass(MultithreadedMapRunner.class);' in MR app
- 'mapred.map.multithreadedrunner.threads = 2' in mapred-site.xml

A simple MR app failed as its Map task encountered ArrayIndexOutOfBoundsException as below(please
ignore the line numbers in the exception as I added some log print codes):
java.lang.ArrayIndexOutOfBoundsException
        at org.apache.hadoop.mapred.MapTask$MapOutputBuffer$Buffer.write(MapTask.java:1331)
        at java.io.DataOutputStream.write(DataOutputStream.java:101)
        at org.apache.hadoop.io.Text.write(Text.java:282)
        at org.apache.hadoop.io.serializer.WritableSerialization$WritableSerializer.serialize(WritableSerialization.java:90)
        at org.apache.hadoop.io.serializer.WritableSerialization$WritableSerializer.serialize(WritableSerialization.java:77)
        at org.apache.hadoop.mapred.MapTask$MapOutputBuffer.collect(MapTask.java:1060)
        at org.apache.hadoop.mapred.MapTask$OldOutputCollector.collect(MapTask.java:591)
        at study.hadoop.mapreduce.sample.WordCount$Map.map(WordCount.java:41)
        at study.hadoop.mapreduce.sample.WordCount$Map.map(WordCount.java:1)
        at org.apache.hadoop.mapred.lib.MultithreadedMapRunner$MapperInvokeRunable.run(MultithreadedMapRunner.java:231)
        at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:897)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:919)
        at java.lang.Thread.run(Thread.java:738)


And the exception happens on line 'System.arraycopy(b, off, kvbuffer, bufindex, len)' in MapTask.java#MapOutputBuffer#Buffer#write().
When the exception occurs, 'b.length=4' but 'len=9'. 

Btw, if I set 'mapred.map.multithreadedrunner.threads = 1', no exception happened. So it should
be an issue caused by multiple threads.


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