Question

I have started a little something on hadoop. It is setup and running properly. Right now I am doing a single node / stand alone cluster.
I am trying to run sample job as mentioned on http://hadoop.apache.org/common/docs/r0.18.3/mapred_tutorial.html

So far, program is correctly compiled, jar has been created, manifest added successfully. But when I try to run the job I get this error.

Exception in thread "main" java.lang.ClassNotFoundException: org.myorg.WordCount
at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:247)
at org.apache.hadoop.util.RunJar.main(RunJar.java:149)

I have copy pasted the exact same program as mentioned in link. But it’s giving this error. This is the command line I hit.

[shantanu@shades1ld1 hadoop]$ bin/hadoop jar /home/shantanu/hadoop/src/examples/wordcount.jar org.myorg.WordCount /tmp/Hadoop_Jobs/ /tmp/Hadoop_Results

I have gone through numerous articles, but couldn’t find an explanation for this, please help.

Answer 1

Are you sure that wordcount.jar contains the org.myorg.WordCount class?

Didn’t you modify the package name?