mongodb/mongo-hadoop — pull request #33 by bpfoster (2012-02-08 16:47:31+00:00)
Title: Make combiner truly optional

While the combiner is marked as optional, if one is not specified, Hadoop throws a NullPointerException (stack trace below).

Exception in thread "main" java.lang.NullPointerException
at java.lang.Class.isAssignableFrom(Native Method)
at org.apache.hadoop.conf.Configuration.setClass(Configuration.java:1069)
at org.apache.hadoop.mapreduce.Job.setCombinerClass(Job.java:152)
at com.mongodb.hadoop.util.MongoTool.run(MongoTool.java:65)
at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:65)
at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:79)
at com.somecompany.mongohadoop.MyDriver.main(MyDriver.java:29)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.apache.hadoop.util.RunJar.main(RunJar.java:197)