I have hadoop cluster version 2.2.0 running with mahout 0.8, is it compatible? Because whenever I run this command:
bin/mahout recommenditembased --input mydata.dat --usersFile user.dat --numRecommendations 2 --output output/ --similarityClassname SIMILARITY_PEARSON_CORRELATION
Give me this error:
Exception in thread "main" java.lang.IncompatibleClassChangeError: Found interface org.apache.hadoop.mapreduce.JobContext, but class was expected
at org.apache.mahout.common.HadoopUtil.getCustomJobName(HadoopUtil.java:174)
at org.apache.mahout.common.AbstractJob.prepareJob(AbstractJob.java:614)
at org.apache.mahout.cf.taste.hadoop.preparation.PreparePreferenceMatrixJob.run(PreparePreferenceMatrixJob.java:75)
at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:70)
at org.apache.mahout.cf.taste.hadoop.item.RecommenderJob.run(RecommenderJob.java:158)
at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:70)
at org.apache.mahout.cf.taste.hadoop.item.RecommenderJob.main(RecommenderJob.java:312)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:622)
at org.apache.hadoop.util.ProgramDriver$ProgramDescription.invoke(ProgramDriver.java:72)
at org.apache.hadoop.util.ProgramDriver.run(ProgramDriver.java:144)
at org.apache.hadoop.util.ProgramDriver.driver(ProgramDriver.java:152)
at org.apache.mahout.driver.MahoutDriver.main(MahoutDriver.java:194)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:622)
at org.apache.hadoop.util.RunJar.main(RunJar.java:212)
Or Im wrong? Any info would be helpful.
No, it does not work with Hadoop 2.x, someone else got the same error message like you.
It seems that at the very least it would require a recompile.
And more people are having the same problems: how can I compile/using mahout for hadoop 2.0?
About an hour ago Mahout has officially added support to Hadoop 2.x in the master branch (see MAHOUT-1329)
Checkout the code here https://github.com/apache/mahout and recompile using:
mvn clean package -Dhadoop2.version=2.2.0
Try and see if that works.
You can get the source code from github https://github.com/apache/mahout and run the following command
mvn -Dhadoop2.version=2.2.0 -DskipTests clean install
Then, you can find the release package in distribution/target/
来源：https://stackoverflow.com/questions/20911821/hadoop-2-2-0-is-compatible-with-mahout-0-8