java - Mahout seqdirectory 不工作

Question

我正在尝试“Mahout Cookbook”的第二章食谱。
这是对一些 lastfm 数据进行排序的第一步。
mahout seqdirectory -i $WORK_DIR/original -o $WORK_DIR/sequencesfiles
该命令应该将原始格式转换为 Mahout 的序列格式。

14/07/23 14:43:10 INFO mapred.LocalJobRunner: map task executor complete.
14/07/23 14:43:10 WARN mapred.LocalJobRunner: job_local1595213196_0001
java.lang.Exception: java.lang.RuntimeException: java.lang.reflect.InvocationTargetException
    at org.apache.hadoop.mapred.LocalJobRunner$Job.runTasks(LocalJobRunner.java:462)
    at org.apache.hadoop.mapred.LocalJobRunner$Job.run(LocalJobRunner.java:522)
Caused by: java.lang.RuntimeException: java.lang.reflect.InvocationTargetException
    at org.apache.hadoop.mapreduce.lib.input.CombineFileRecordReader.initNextRecordReader(CombineFileRecordReader.java:166)
    at org.apache.hadoop.mapreduce.lib.input.CombineFileRecordReader.<init>(CombineFileRecordReader.java:126)
    at org.apache.mahout.text.MultipleTextFileInputFormat.createRecordReader(MultipleTextFileInputFormat.java:43)
    at org.apache.hadoop.mapred.MapTask$NewTrackingRecordReader.<init>(MapTask.java:492)
    at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:735)
    at org.apache.hadoop.mapred.MapTask.run(MapTask.java:340)
    at org.apache.hadoop.mapred.LocalJobRunner$Job$MapTaskRunnable.run(LocalJobRunner.java:243)
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.reflect.InvocationTargetException
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:408)
    at org.apache.hadoop.mapreduce.lib.input.CombineFileRecordReader.initNextRecordReader(CombineFileRecordReader.java:157)
    ... 11 more
Caused by: java.lang.IncompatibleClassChangeError: Found interface org.apache.hadoop.mapreduce.TaskAttemptContext, but class was expected
    at org.apache.mahout.text.WholeFileRecordReader.<init>(WholeFileRecordReader.java:59)

Answer 1

检查此错误:

Caused by: java.lang.IncompatibleClassChangeError: Found interface org.apache.hadoop.mapreduce.TaskAttemptContext, but class was expected
    at org.apache.mahout.text.WholeFileRecordReader.<init>(WholeFileRecordReader.java:59)

这意味着，您的 Hadoop 版本与 Mahout 的预期不同。

Hadoop: java.lang.IncompatibleClassChangeError: Found interface org.apache.hadoop.mapreduce.JobContext, but class was expected

检查一次您的安装。