问题
I am new to hadoop and not to say mahout. I hope someone could assist me to get through here.. have been trying for 2 days..
I have already a hadoop cluster running.
I am using hadoop-2.0.0-alpha.
I installed mahout (ahout-distribution-0.7) and maven-2.2.1 (latest maven-3.0.4 doesnt work)
Now i would like to just run mahout to get the idea of what is it.
I learnt that by typing "mahout" it will print out a list of options (algorithms) available in mahout, but when i typed mahout, it just gives me Java Exception.
$ [hadoop@localhost bin]$ mahout
MAHOUT_LOCAL is not set; adding HADOOP_CONF_DIR to classpath.
Running on hadoop, using /home/hadoop/hadoop/bin/hadoop and HADOOP_CONF_DIR=/home/hadoop/hadoop/conf
MAHOUT-JOB: /home/hadoop/mahout/examples/target/mahout-examples-0.7-job.jar
Exception in thread "main" java.lang.NoSuchMethodError: org.apache.hadoop.util.ProgramDriver.driver([Ljava/lang/String;)V
at org.apache.mahout.driver.MahoutDriver.main(MahoutDriver.java:123)
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:616)
at org.apache.hadoop.util.RunJar.main(RunJar.java:208)
From what i googled online, most of the answers required me to use lower version of hadoop, ie hadoop-0.20, Is my problem now has something to do with my hadoop version?
Thank you.
======== NEWLY EDITED ========
I changed my hadoop version to hadoop-1.0.3 and now it works when i typed "mahout" (my mahout is version7)
But it fails again with the similar error, when i tried to run an example..
$ hadoop /home/hadoop/mahout/core/target/mahout-core-0.7-job.jar org.apache.mahout.cf.taste.hadoop.item.RecommenderJob -Dmapred.output.dir=output -Dmapred.input.dir=input/prefs.txt --usersFile input/users.txt --similarityClassname SIMILARITY_PEARSON_CORRELATION
Caused by: java.lang.ClassNotFoundException: .home.hadoop.mahout.core.target.mahout-core-0.7-job.jar
at java.net.URLClassLoader$1.run(URLClassLoader.java:217)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
at java.lang.ClassLoader.loadClass(ClassLoader.java:321)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:294)
at java.lang.ClassLoader.loadClass(ClassLoader.java:266)
Could not find the main class: /home/hadoop/mahout/core/target/mahout-core-0.7-job.jar. Program will exit.
Hmm..
回答1:
Yes it looks like you need to use a different version of Hadoop (or build the latest Mahout from source) if you want this to work. You got a NoSuchMethodError so the first thing to do is check if the ProgramDriver is in the distribution of hadoop you're using.
Looking at the API docs for the various version you can see that its in v0.0.20.x but had been removed from the newer versions.
- http://hadoop.apache.org/common/docs/r0.20.205.0/api/index.html
- http://hadoop.apache.org/common/docs/r2.0.0-alpha/api/index.html (your version)
Looking at the JIRA for Mahout you can see a bug was submitted for a similar problem to this on July 11th and has been fixed in version 0.8.
- [MAHOUT-1044] https://issues.apache.org/jira/browse/MAHOUT-1044
Update:
Shouldn't your command have jar after the hadoop command? Something like:
$ hadoop jar /home/hadoop/mahout/core/target/mahout-core-0.7-job.jar etc
回答2:
@BinaryNerd is right. There is a bug in Mahout as detailed in:
- [MAHOUT-1044] https://issues.apache.org/jira/browse/MAHOUT-1044
Mahout 0.7 command line gives the NoClassDef ProgramDriver error as detailed in the first part of your question. This will be fixed in 0.8 or you can edit your bin/mahout as detailed in the bug report to fix the brace placement.
I ran into the same issue using mahout under Cloudera CDH 4.1.2. Changing the brace in my bin/mahout fixed it.
来源：https://stackoverflow.com/questions/11751763/mahout-wont-start-up-anything-to-do-with-compatible-version-between-hadoop-and