[MAHOUT-1314] StreamingKMeansReducer throws NullPointerException when REDUCE_STREAMING_KMEANS is set to true

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.8
• Fix Version/s: 0.9
• Component/s: classic
• Assignee: Suneel Marthi
• Reporter: Adi Haviv
• Created: 18/Aug/13 14:07
• Updated: 31/Jan/24 22:14
• Resolved: 18/Nov/13 07:53

Description

when REDUCE_STREAMING_KMEANS option is set to true (-rskm) the reducer fails with NullPointerException.

the problem is in the reduce method itself: on line 60 ( return input.getCentroid(); )
it should be input.getCentroid().clone();
similar to line 81.

full stack trace:
java.lang.NullPointerException
at com.google.common.base.Preconditions.checkNotNull(Preconditions.java:191)
at org.apache.mahout.math.random.WeightedThing.<init>(WeightedThing.java:31)
at org.apache.mahout.math.neighborhood.BruteSearch.searchFirst(BruteSearch.java:133)
at org.apache.mahout.clustering.ClusteringUtils.estimateDistanceCutoff(ClusteringUtils.java:100)
at org.apache.mahout.clustering.streaming.mapreduce.StreamingKMeansThread.call(StreamingKMeansThread.java:64)
at org.apache.mahout.clustering.streaming.mapreduce.StreamingKMeansReducer.reduce(StreamingKMeansReducer.java:66)
at org.apache.mahout.clustering.streaming.mapreduce.StreamingKMeansReducer.reduce(StreamingKMeansReducer.java:1)
at org.apache.hadoop.mapreduce.Reducer.run(Reducer.java:176)
at org.apache.hadoop.mapred.ReduceTask.runNewReducer(ReduceTask.java:650)
at org.apache.hadoop.mapred.ReduceTask.run(ReduceTask.java:418)
at org.apache.hadoop.mapred.LocalJobRunner$Job.run(LocalJobRunner.java:260)

it happens every time the REDUCE_STREAMING_KMEANS is set to true.