java - Mahout 0.9 和 Hadoop 2.2.0 - 找到接口(interface) org.apache.hadoop.mapreduce.JobContext，但类是预期的

Question

我的代码哪里出错了？当我搜索时，我发现了一个类似的帖子，但无法适应我的问题。

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:73)
    at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:70)
    at org.apache.mahout.cf.taste.hadoop.item.RecommenderJob.run(RecommenderJob.java:164)
    at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:70)
    at org.apache.mahout.cf.taste.hadoop.item.RecommenderJob.main(RecommenderJob.java:322)
    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:606)
    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:195)
    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:606)
    at org.apache.hadoop.util.RunJar.main(RunJar.java:212)

Answer 1

我认为这是一个已知问题，将在 Mahout 1.0 中提供。如果你想要支持 Hadoop 2.x，你可以尝试从 trunk 重新编译 mahout。

已修复此 JIRA 票证:https://issues.apache.org/jira/browse/MAHOUT-1329

另请参阅另一个类似问题:Mahout error with Hadoop2.2