RuntimeException，ClassNotFoundException：类WordCount $找不到Map。 Mapper类问题

时间：2016-08-12 04:31:59

标签： java mapreduce classnotfoundexception hortonworks-data-platform word-count

我正在尝试在sandBox HortonWork HDP上运行WordCount。我在许多地方搜索过这个错误并应用了他们所说的内容而我无法使其运行。

一步一步： 1-首先我编译java程序

javac -cp .:$(hadoop classpath) WordCount.java

2- Next将类捆绑为jar文件

jar cvf WordCount.jar *.class

3-让我们看一下jar文件的内容：

jar tf WordCount.jar

META-INF/
META-INF/MANIFEST.MF
WordCount.class
WordCount$Map.class
WordCount$Reduce.class

4-接下来将输入文件设置为hdfs并运行作业。

hdfs dfs -put file.txt

hadoop jar WordCount.jar WordCount /user/root/file.txt /user/root/output

5-我收到以下错误：

WARNING: Use "yarn jar" to launch YARN applications.
16/08/12 04:02:49 INFO impl.TimelineClientImpl: Timeline service address: http://sandbox.hortonworks.com:8188/ws/v1/timeline/
16/08/12 04:02:49 INFO client.RMProxy: Connecting to ResourceManager at sandbox.hortonworks.com/10.0.2.15:8050
16/08/12 04:02:50 WARN mapreduce.JobResourceUploader: No job jar file set.  User classes may not be found. See Job or Job#setJar(String).
16/08/12 04:02:50 INFO input.FileInputFormat: Total input paths to process : 1
16/08/12 04:02:51 INFO mapreduce.JobSubmitter: number of splits:1
16/08/12 04:02:51 INFO mapreduce.JobSubmitter: Submitting tokens for job: job_1470929339157_0022
16/08/12 04:02:51 INFO mapred.YARNRunner: Job jar is not present. Not adding any jar to the list of resources.
16/08/12 04:02:51 INFO impl.YarnClientImpl: Submitted application application_1470929339157_0022
16/08/12 04:02:52 INFO mapreduce.Job: The url to track the job: http://sandbox.hortonworks.com:8088/proxy/application_1470929339157_0022/
16/08/12 04:02:52 INFO mapreduce.Job: Running job: job_1470929339157_0022
16/08/12 04:03:03 INFO mapreduce.Job: Job job_1470929339157_0022 running in uber mode : false
16/08/12 04:03:03 INFO mapreduce.Job:  map 0% reduce 0%
16/08/12 04:03:10 INFO mapreduce.Job:  map 100% reduce 0%
16/08/12 04:03:10 INFO mapreduce.Job: Task Id : attempt_1470929339157_0022_m_000000_0, Status : FAILED
Error: java.lang.RuntimeException: java.lang.ClassNotFoundException: Class WordCount$Map not found
    at org.apache.hadoop.conf.Configuration.getClass(Configuration.java:2195)
    at org.apache.hadoop.mapreduce.task.JobContextImpl.getMapperClass(JobContextImpl.java:186)
    at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:745)
    at org.apache.hadoop.mapred.MapTask.run(MapTask.java:341)
    at org.apache.hadoop.mapred.YarnChild$2.run(YarnChild.java:168)
    at java.security.AccessController.doPrivileged(Native Method)
    at javax.security.auth.Subject.doAs(Subject.java:415)
    at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1657)
    at org.apache.hadoop.mapred.YarnChild.main(YarnChild.java:162)
Caused by: java.lang.ClassNotFoundException: Class WordCount$Map not found
    at org.apache.hadoop.conf.Configuration.getClassByName(Configuration.java:2101)
    at org.apache.hadoop.conf.Configuration.getClass(Configuration.java:2193)
    ... 8 more

16/08/12 04:03:11 INFO mapreduce.Job:  map 0% reduce 0%
16/08/12 04:03:16 INFO mapreduce.Job: Task Id : attempt_1470929339157_0022_m_000000_1, Status : FAILED
Error: java.lang.RuntimeException: java.lang.ClassNotFoundException: Class WordCount$Map not found
    at org.apache.hadoop.conf.Configuration.getClass(Configuration.java:2195)
    at org.apache.hadoop.mapreduce.task.JobContextImpl.getMapperClass(JobContextImpl.java:186)
    at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:745)
    at org.apache.hadoop.mapred.MapTask.run(MapTask.java:341)
    at org.apache.hadoop.mapred.YarnChild$2.run(YarnChild.java:168)
    at java.security.AccessController.doPrivileged(Native Method)
    at javax.security.auth.Subject.doAs(Subject.java:415)
    at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1657)
    at org.apache.hadoop.mapred.YarnChild.main(YarnChild.java:162)
Caused by: java.lang.ClassNotFoundException: Class WordCount$Map not found
    at org.apache.hadoop.conf.Configuration.getClassByName(Configuration.java:2101)
    at org.apache.hadoop.conf.Configuration.getClass(Configuration.java:2193)
    ... 8 more

16/08/12 04:03:23 INFO mapreduce.Job: Task Id : attempt_1470929339157_0022_m_000000_2, Status : FAILED
Error: java.lang.RuntimeException: java.lang.ClassNotFoundException: Class WordCount$Map not found
    at org.apache.hadoop.conf.Configuration.getClass(Configuration.java:2195)
    at org.apache.hadoop.mapreduce.task.JobContextImpl.getMapperClass(JobContextImpl.java:186)
    at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:745)
    at org.apache.hadoop.mapred.MapTask.run(MapTask.java:341)
    at org.apache.hadoop.mapred.YarnChild$2.run(YarnChild.java:168)
    at java.security.AccessController.doPrivileged(Native Method)
    at javax.security.auth.Subject.doAs(Subject.java:415)
    at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1657)
    at org.apache.hadoop.mapred.YarnChild.main(YarnChild.java:162)
Caused by: java.lang.ClassNotFoundException: Class WordCount$Map not found
    at org.apache.hadoop.conf.Configuration.getClassByName(Configuration.java:2101)
    at org.apache.hadoop.conf.Configuration.getClass(Configuration.java:2193)
    ... 8 more

16/08/12 04:03:31 INFO mapreduce.Job:  map 100% reduce 100%
16/08/12 04:03:31 INFO mapreduce.Job: Job job_1470929339157_0022 failed with state FAILED due to: Task failed task_1470929339157_0022_m_000000
Job failed as tasks failed. failedMaps:1 failedReduces:0

16/08/12 04:03:31 INFO mapreduce.Job: Counters: 13
    Job Counters 
        Failed map tasks=4
        Killed reduce tasks=1
        Launched map tasks=4
        Other local map tasks=3
        Data-local map tasks=1
        Total time spent by all maps in occupied slots (ms)=20865
        Total time spent by all reduces in occupied slots (ms)=0
        Total time spent by all map tasks (ms)=20865
        Total time spent by all reduce tasks (ms)=0
        Total vcore-seconds taken by all map tasks=20865
        Total vcore-seconds taken by all reduce tasks=0
        Total megabyte-seconds taken by all map tasks=5216250
        Total megabyte-seconds taken by all reduce tasks=0

`

以下代码是我尝试运行的代码：

import java.io.IOException;
import java.util.*;

import org.apache.hadoop.conf.*;
import org.apache.hadoop.fs.*;
import org.apache.hadoop.conf.*;
import org.apache.hadoop.io.*;
import org.apache.hadoop.mapreduce.*;
import org.apache.hadoop.mapreduce.lib.input.*;
import org.apache.hadoop.mapreduce.lib.output.*;
import org.apache.hadoop.util.*;

public class WordCount extends Configured implements Tool {

  public static void main(String args[]) throws Exception {
    int res = ToolRunner.run(new WordCount(), args);
    System.exit(res);
  }

  public int run(String[] args) throws Exception {
    Path inputPath = new Path(args[0]);
    Path outputPath = new Path(args[1]);

    Configuration conf = getConf();
    Job job = new Job(conf, this.getClass().toString());
    job.setJarByClass(WordCount.class);

    FileInputFormat.setInputPaths(job, inputPath);
    FileOutputFormat.setOutputPath(job, outputPath);

    job.setJobName("WordCount");
    //job.setJarByClass(WordCount.class);

    job.setMapperClass(Map.class);
    job.setCombinerClass(Reduce.class);
    job.setReducerClass(Reduce.class);
    job.setMapOutputKeyClass(Text.class);
    job.setMapOutputValueClass(IntWritable.class);
    job.setOutputKeyClass(Text.class);
    job.setOutputValueClass(IntWritable.class);
    job.setInputFormatClass(TextInputFormat.class);
    job.setOutputFormatClass(TextOutputFormat.class);
    //FileInputFormat.setInputPaths(job, inputPath);
    //FileOutputFormat.setOutputPath(job, outputPath);

   return job.waitForCompletion(true) ? 0 : 1;
  }

  public static class Map extends Mapper<LongWritable, Text, Text, IntWritable> {
    private final static IntWritable one = new IntWritable(1);
    private Text word = new Text();

    @Override
    public void map(LongWritable key, Text value,
                    Mapper.Context context) throws IOException, InterruptedException {
      String line = value.toString();
      StringTokenizer tokenizer = new StringTokenizer(line);
      while (tokenizer.hasMoreTokens()) {
        word.set(tokenizer.nextToken());
        context.write(word, one);
      }
    }
  }

  public static class Reduce extends Reducer<Text, IntWritable, Text, IntWritable> {

    @Override
    public void reduce(Text key, Iterable<IntWritable> values, Context context) throws IOException, InterruptedException {
      int sum = 0;
      for (IntWritable value : values) {
        sum += value.get();
      }

      context.write(key, new IntWritable(sum));
    }
  }

}

提前感谢任何帮助/提示和建议。

3 个答案:

答案 0 :(得分：7)

尝试在课堂上添加以下内容

job.setJar("WordCount.jar");

答案 1 :(得分：1)

像这样运行mapreduce jar：

HADOOP_CLASSPATH=$HADOOP_CLASSPATH:/path/to/the/jar/examples.jar; 
hadoop jar /path/to/the/jar/examples.jar WordCount /data/tmp/input1.txt /data/tmp/output2

答案 2 :(得分：0)

变体且不容易出错的解决方案是使用以下内容：

job.setJarByClass(WordCount.class);

请确保您也拨打以下电话以避免停止您的计划：

job.waitForCompletion(true);
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