[MAPREDUCE-1178] MultipleInputs fails with ClassCastException

• Type: Bug
• Status: Closed
• Priority: Blocker
• Resolution: Fixed
• Affects Version/s: 0.21.0
• Fix Version/s: 0.21.0
• Hadoop Flags: Reviewed
• Assignee: Amareshwari Sriramadasu
• Reporter: Jay Booth
• Created: 02/Nov/09 23:07
• Updated: 24/Aug/10 21:19
• Resolved: 09/Nov/09 08:02

Description

When running MultipleInputs against the new API, we get failures with this ClassCastException:

java.lang.ClassCastException: org.apache.hadoop.mapreduce.lib.input.TaggedInputSplit cannot be cast to org.apache.hadoop.mapreduce.lib.input.FileSplit
at org.apache.hadoop.mapreduce.lib.input.LineRecordReader.initialize(LineRecordReader.java:70)
at org.apache.hadoop.mapreduce.lib.input.KeyValueLineRecordReader.initialize(KeyValueLineRecordReader.java:59)
at org.apache.hadoop.mapred.MapTask$NewTrackingRecordReader.initialize(MapTask.java:439)
at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:599)
at org.apache.hadoop.mapred.MapTask.run(MapTask.java:323)
at org.apache.hadoop.mapred.LocalJobRunner$Job.run(LocalJobRunner.java:257)

The unit test for MultipleInputs doesn't actually run a job so this snuck through while still passing the unit test. Attached patch fixes the unit test to expose the failure and does a little casting kung-fu in LineRecordReader to avoid the error.