Trivial Description
The SequenceFile#handleChecksumException assumes the conf data member has been set. It will not be set if we use the 'Reader(FileSystem fs, Path file, int bufferSize, long start, long length)' constructor. The latter is used by ReduceTask Sorter:
java.lang.NullPointerException
at org.apache.hadoop.io.SequenceFile$Reader.handleChecksumException(SequenceFile.java:407)
at org.apache.hadoop.io.SequenceFile$Reader.next(SequenceFile.java:400)
at org.apache.hadoop.io.SequenceFile$Sorter$MergeStream.next(SequenceFile.java:837)
at org.apache.hadoop.io.SequenceFile$Sorter$MergeQueue.merge(SequenceFile.java:881)
at org.apache.hadoop.io.SequenceFile$Sorter$MergePass.run(SequenceFile.java:766)
at org.apache.hadoop.io.SequenceFile$Sorter.mergePass(SequenceFile.java:702)
at org.apache.hadoop.io.SequenceFile$Sorter.sort(SequenceFile.java:528)
at org.apache.hadoop.mapred.ReduceTask.run(ReduceTask.java:253)
at org.apache.hadoop.mapred.TaskTracker$Child.main(TaskTracker.java:787)