hadoop:classnotfound异常：wordcount$map

cgh8pdjw  于 2021-06-02  发布在  Hadoop
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我使用hadoop版本hadoop-0.20.205.0来测试wordcount示例。我构建了jar文件，并尝试使用以下命令运行它：

  1. hadoop Jar myJar.jar wordCount input output

然而，我得到了这个例外：似乎Map器和减速器已经启动，因为你可以看到在日志中有“Map0%减少0%”。

  1. 15/08/10 11:53:27 WARN mapred.JobClient: Use GenericOptionsParser for parsing the arguments. Applications should implement Tool for the same.
  2. 15/08/10 11:53:27 WARN mapred.JobClient: No job jar file set.  User classes may not be found. See JobConf(Class) or JobConf#setJar(String).
  3. 15/08/10 11:53:27 INFO input.FileInputFormat: Total input paths to process : 1
  4. 15/08/10 11:53:28 INFO mapred.JobClient: Running job: job_201508100953_0021
  5. 15/08/10 11:53:29 INFO mapred.JobClient:  map 0% reduce 0%
  6. 15/08/10 11:53:41 INFO mapred.JobClient: Task Id : attempt_201508100953_0021_m_000000_0, Status : FAILED
  7. java.lang.RuntimeException: java.lang.ClassNotFoundException: WordCount$Map
  8.     at org.apache.hadoop.conf.Configuration.getClass(Configuration.java:866)
  9.     at org.apache.hadoop.mapreduce.JobContext.getMapperClass(JobContext.java:199)
  10.     at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:719)
  11.     at org.apache.hadoop.mapred.MapTask.run(MapTask.java:370)
  12.     at org.apache.hadoop.mapred.Child$4.run(Child.java:255)
  13.     at java.security.AccessController.doPrivileged(Native Method)
  14.     at javax.security.auth.Subject.doAs(Subject.java:415)
  15.     at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1059)
  16.     at org.apache.hadoop.mapred.Child.main(Child.java:249)
  17. Caused by: java.lang.ClassNotFoundException: WordCount$Map
  18.     at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
  19.     at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
  20.     at java.security.AccessController.doPrivileged(Native Method)
  21.     at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
  22.     at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
  23.     at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
  24.     at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
  25.     at java.lang.Class.forName0(Native Method)
  26.     at java.lang.Class.forName(Class.java:274)
  27.     at org.apache.hadoop.conf.Configuration.getClassByName(Configuration.java:819)
  28.     at org.apache.hadoop.conf.Configuration.getClass(Configuration.java:864)
  29.     ... 8 more
  31. 15/08/10 11:53:47 INFO mapred.JobClient: Task Id : attempt_201508100953_0021_m_000000_1, Status : FAILED
  32. java.lang.RuntimeException: java.lang.ClassNotFoundException: WordCount$Map
  33.     at org.apache.hadoop.conf.Configuration.getClass(Configuration.java:866)
  34.     at org.apache.hadoop.mapreduce.JobContext.getMapperClass(JobContext.java:199)
  35.     at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:719)
  36.     at org.apache.hadoop.mapred.MapTask.run(MapTask.java:370)
  37.     at org.apache.hadoop.mapred.Child$4.run(Child.java:255)
  38.     at java.security.AccessController.doPrivileged(Native Method)
  39.     at javax.security.auth.Subject.doAs(Subject.java:415)
  40.     at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1059)
  41.     at org.apache.hadoop.mapred.Child.main(Child.java:249)
  42. Caused by: java.lang.ClassNotFoundException: WordCount$Map
  43.     at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
  44.     at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
  45.     at java.security.AccessController.doPrivileged(Native Method)
  46.     at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
  47.     at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
  48.     at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
  49.     at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
  50.     at java.lang.Class.forName0(Native Method)
  51.     at java.lang.Class.forName(Class.java:274)
  52.     at org.apache.hadoop.conf.Configuration.getClassByName(Configuration.java:819)
  53.     at org.apache.hadoop.conf.Configuration.getClass(Configuration.java:864)
  54.     ... 8 more
  56. 15/08/10 11:53:53 INFO mapred.JobClient: Task Id : attempt_201508100953_0021_m_000000_2, Status : FAILED
  57. java.lang.RuntimeException: java.lang.ClassNotFoundException: WordCount$Map
  58.     at org.apache.hadoop.conf.Configuration.getClass(Configuration.java:866)
  59.     at org.apache.hadoop.mapreduce.JobContext.getMapperClass(JobContext.java:199)
  60.     at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:719)
  61.     at org.apache.hadoop.mapred.MapTask.run(MapTask.java:370)
  62.     at org.apache.hadoop.mapred.Child$4.run(Child.java:255)
  63.     at java.security.AccessController.doPrivileged(Native Method)
  64.     at javax.security.auth.Subject.doAs(Subject.java:415)
  65.     at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1059)
  66.     at org.apache.hadoop.mapred.Child.main(Child.java:249)
  67. Caused by: java.lang.ClassNotFoundException: WordCount$Map
  68.     at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
  69.     at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
  70.     at java.security.AccessController.doPrivileged(Native Method)
  71.     at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
  72.     at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
  73.     at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
  74.     at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
  75.     at java.lang.Class.forName0(Native Method)
  76.     at java.lang.Class.forName(Class.java:274)
  77.     at org.apache.hadoop.conf.Configuration.getClassByName(Configuration.java:819)
  78.     at org.apache.hadoop.conf.Configuration.getClass(Configuration.java:864)
  79.     ... 8 more
  81. 15/08/10 11:54:05 INFO mapred.JobClient: Job complete: job_201508100953_0021
  82. 15/08/10 11:54:05 INFO mapred.JobClient: Counters: 7
  83. 15/08/10 11:54:05 INFO mapred.JobClient:   Job Counters 
  84. 15/08/10 11:54:05 INFO mapred.JobClient:     SLOTS_MILLIS_MAPS=25289
  85. 15/08/10 11:54:05 INFO mapred.JobClient:     Total time spent by all reduces waiting after reserving slots (ms)=0
  86. 15/08/10 11:54:05 INFO mapred.JobClient:     Total time spent by all maps waiting after reserving slots (ms)=0
  87. 15/08/10 11:54:05 INFO mapred.JobClient:     Launched map tasks=4
  88. 15/08/10 11:54:05 INFO mapred.JobClient:     Data-local map tasks=4
  89. 15/08/10 11:54:05 INFO mapred.JobClient:     SLOTS_MILLIS_REDUCES=0
  90. 15/08/10 11:54:05 INFO mapred.JobClient:     Failed map tasks=1
  92. real    0m42.316s
  93. user    0m0.980s
  94. sys 0m2.828s

这是我的密码：

  1. import java.io.IOException;
  2. import java.util.*;
  4. import org.apache.hadoop.fs.Path;
  5. import org.apache.hadoop.conf.*;
  6. import org.apache.hadoop.io.*;
  7. import org.apache.hadoop.mapreduce.*;
  8. import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
  9. import org.apache.hadoop.mapreduce.lib.input.TextInputFormat;
  10. import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
  11. import org.apache.hadoop.mapreduce.lib.output.TextOutputFormat;
  13. public class WordCount {
  15.     public static class Map extends Mapper<LongWritable, Text, Text, IntWritable> {
  16.         private final static IntWritable one = new IntWritable(1);
  17.         private Text word = new Text();
  19.         public void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException {
  20.             String line = value.toString();
  21.             StringTokenizer tokenizer = new StringTokenizer(line);
  22.             while (tokenizer.hasMoreTokens()) {
  23.                 word.set(tokenizer.nextToken());
  24.                 context.write(word, one);
  25.             }
  26.         }
  27.     }
  29.     public static class Reduce extends Reducer<Text, IntWritable, Text, IntWritable> {
  31.         public void reduce(Text key, Iterable<IntWritable> values, Context context)
  32.                 throws IOException, InterruptedException {
  33.             int sum = 0;
  34.             for (IntWritable val : values) {
  35.                 sum += val.get();
  36.             }
  37.             context.write(key, new IntWritable(sum));
  38.         }
  39.     }
  41.     public static void main(String[] args) throws Exception {
  42.         Configuration conf = new Configuration();
  43.         conf.addResource(new Path("/HADOOP_HOME/conf/core-site.xml"));
  44.         conf.addResource(new Path("/HADOOP_HOME/conf/hdfs-site.xml"));
  45.         Job job = new Job(conf, "wordcount");
  47.         job.setOutputKeyClass(Text.class);
  48.         job.setOutputValueClass(IntWritable.class);
  50.         job.setMapperClass(Map.class);
  51.         job.setReducerClass(Reduce.class);
  53.         job.setInputFormatClass(TextInputFormat.class);
  54.         job.setOutputFormatClass(TextOutputFormat.class);
  56.         FileInputFormat.addInputPath(job, new Path(args[0]));
  57.         FileOutputFormat.setOutputPath(job, new Path(args[1]));
  59.         job.waitForCompletion(true);
  60.     }
  62. }
hadoopmapreduceJar

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