Jinghui Wang created HADOOP-11334:
-------------------------------------

             Summary: Mapreduce Job Failed due to failure fetching mapper 
output on the reduce side
                 Key: HADOOP-11334
                 URL: https://issues.apache.org/jira/browse/HADOOP-11334
             Project: Hadoop Common
          Issue Type: Bug
          Components: io
    Affects Versions: 2.4.1
            Reporter: Jinghui Wang


Running terasort with the following options hadoop jar 
hadoop-mapreduce-examples.jar terasort *-Dio.native.lib.available=false 
-Dmapreduce.map.output.compress=true 
-Dmapreduce.map.output.compress.codec=org.apache.hadoop.io.compress.GzipCodec*  
/tmp/tera-in /tmp/tera-out

The job failed with the reducer failed to fetching the output from mappers (see 
the following stacktrace). The problem is that in JIRA MAPREDUCE-1784, it added 
support to handle null compressors to default to non-compressed output. In this 
case, when the *io.native.lib.available* is set to true, the compressor will be 
null. However, the decompressor has a Java implementation, so when the reducer 
tries to read the mapper output, it uses the decompressor, but the output does 
not have the Gzip header.



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