The org.apache.mahout.clustering.classify.ClusterClassifier.readPolicy method leaks file handles.
This leak causes a serious problems in setups that reuse JVMs for multiple tasks (as with "mapred.job.reuse.jvm.num.tasks").
In more detail:
The org.apache.mahout.clustering.classify.ClusterClassifier class has static methods to read policies: readPolicy.
It opens a SequenceFile.Reader and reads from it, and then neglects to close it.
add a call to reader.close() before the return statement in readPolicy