错误：java.lang.RuntimeException：java.lang.ClassNotFoundException：类WordCountExample $ Map未找到

Question

I am using ubuntu system and trying to run wordcount.jar program. Unfortunately, I am having the following error -

Error: java.lang.RuntimeException: java.lang.ClassNotFoundException: Class WordCountExample$Map not found

I have updated the classpath as it is -

job.setJarByClass(WordCountExample.class); and jobconf.setJarByClass(WordCountExample.class);

None of this work. Don't know what is wrong. Please share your expatriate in this regards.

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

import org.apache.hadoop.fs.Path;
import org.apache.hadoop.conf.*;
import org.apache.hadoop.io.*;
import org.apache.hadoop.mapreduce.*;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.input.TextInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.mapreduce.lib.output.TextOutputFormat;

/** * @author http://www.devinline.com */

public class WordCountExample {
/* Map class which job will use and execute it map method */
public static class Map extends
Mapper<LongWritable, Text, Text, IntWritable> {
private final static IntWritable one = new IntWritable(1);
private Text word = new Text();

public void map(LongWritable key, Text value, 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);
}}}

/* Reduce class which job will use and execute it reduce method */
public static class Reduce extends
Reducer<Text, IntWritable, Text, IntWritable> {

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

public static void main(String[] args) throws Exception {
Configuration conf = new Configuration();

/* Created a job with name wordCountExample */
Job job = Job.getInstance(conf, "wordCountExample");
job.setJarByClass(WordCountExample.class);  

/*
* Handler string and int in hadoop way: for string hadoop uses Text
* class and for int uses IntWritable */
job.setOutputKeyClass(Text.class);
job.setOutputValueClass(IntWritable.class);

/*
 * Configure map and reducer class, based on which it uses map and
    /* reduce method
     */
job.setMapperClass(Map.class);
job.setReducerClass(Reduce.class);

    /* Input and output format set as TextInputFormat */
job.setInputFormatClass(TextInputFormat.class);
job.setOutputFormatClass(TextOutputFormat.class);

    /* addInputPath - passes input file path to job */
FileInputFormat.addInputPath(job, new Path(args[0]));
    /* setOutputPath - passes output path to job */
FileOutputFormat.setOutputPath(job, new Path(args[1]));

    /* Submit the job to the cluster and wait for it to finish. */
System.exit(job.waitForCompletion(true) ? 1 : 0);
}}

hadoop jar /home/nahmed/WordcountSample.jar WordCountExample /user/nahmed/pg20417.txt /user/nahmed/WCoutput 19/08/15 21:31:12 INFO client.RMProxy: Connecting to ResourceManager at it066431.massey.ac.nz/130.123.248.83:8050

19/08/15 21:31:12 INFO client.AHSProxy: Connecting to Application History server at it066431.massey.ac.nz/130.123.248.83:10200 19/08/15 21:31:12 WARN mapreduce.JobResourceUploader: Hadoop command-line option parsing not performed. Implement the Tool interface and execute your application with ToolRunner to remedy this. 19/08/15 21:31:12 WARN mapreduce.JobResourceUploader: No job jar file set. User classes may not be found. See Job or Job#setJar(String). 19/08/15 21:31:12 INFO input.FileInputFormat: Total input paths to process : 1 19/08/15 21:31:12 INFO mapreduce.JobSubmitter: number of splits:1 19/08/15 21:31:12 INFO mapreduce.JobSubmitter: Submitting tokens for job: job_1562128011754_0026 19/08/15 21:31:13 INFO mapred.YARNRunner: Job jar is not present. Not adding any jar to the list of resources. 19/08/15 21:31:13 INFO impl.YarnClientImpl: Submitted application application_1562128011754_0026 19/08/15 21:31:13 INFO mapreduce.Job: The url to track the job: http://it066431.massey.ac.nz:8088/proxy/application_1562128011754_0026/ 19/08/15 21:31:13 INFO mapreduce.Job: Running job: job_1562128011754_0026 19/08/15 21:31:17 INFO mapreduce.Job: Job job_1562128011754_0026 running in uber mode : false 19/08/15 21:31:17 INFO mapreduce.Job: map 0% reduce 0% 19/08/15 21:31:20 INFO mapreduce.Job: Task Id : attempt_1562128011754_0026_m_000000_0, Status : FAILED Error: java.lang.RuntimeException: java.lang.ClassNotFoundException: Class WordCountExample$Map not found at org.apache.hadoop.conf.Configuration.getClass(Configuration.java:2228) 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$2.run(Y arnChild.java:170) at java.security.AccessController.doPrivileged(Native Method) at javax.security.auth.Subject.doAs(Subject.java:422) at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1866) at org.apache.hadoop.mapred.YarnChild.main(YarnChild.java:164) Caused by: java.lang.ClassNotFoundException: Class WordCountExample$Map not found at org.apache.hadoop.conf.Configuration.getClassByName(Configuration.java:2134) at org.apache.hadoop.conf.Configuration.getClass(Configuration.java:2226) ... 8 more

Container killed by the ApplicationMaster. Container killed on request. Exit code is 143 Container exited with a non-zero exit code 143

19/08/15 21:31:23 INFO mapreduce.Job: Task Id : attempt_1562128011754_0026_m_000000_1, Status : FAILED Error: java.lang.RuntimeException: java.lang.ClassNotFoundException: Class WordCountExample$Map not found at org.apache.hadoop.conf.Configuration.getClass(Configuration.java:2228) 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$2.run(YarnChild.java:170) at java.security.AccessController.doPrivileged(Native Method) at javax.security.auth.Subject.doAs(Subject.java:422) at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1866) at org.apache.hadoop.mapred.YarnChild.main(YarnChild.java:164) Caused by: java.lang.ClassNotFoundException: Class WordCountExample$Map not found at org.apache.hadoop.conf.Configuration.getClassByName(Configuration.java:2134) at org.a pache.hadoop.conf.Configuration.getClass(Configuration.java:2226) ... 8 more

Container killed by the ApplicationMaster. Container killed on request. Exit code is 143 Container exited with a non-zero exit code 143

19/08/15 21:31:26 INFO mapreduce.Job: Task Id : attempt_1562128011754_0026_m_000000_2, Status : FAILED Error: java.lang.RuntimeException: java.lang.ClassNotFoundException: Class WordCountExample$Map not found at org.apache.hadoop.conf.Configuration.getClass(Configuration.java:2228) 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$2.run(YarnChild.java:170) at java.security.AccessController.doPrivileged(Native Method) at javax.security.auth.Subject.doAs(Subject.java:422) at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1866) at org.apache.hadoop.mapred.YarnChild.main(YarnChild.java:164) Caused by: java.lang.ClassNotFoundException: Class WordCountExample$Map not found at org.apache.hadoop.conf.Configuration.getClassByName(Configuration.java:2134) at org.a pache.hadoop.conf.Configuration.getClass(Configuration.java:2226) ... 8 more

Container killed by the ApplicationMaster. Container killed on request. Exit code is 143 Container exited with a non-zero exit code 143

19/08/15 21:31:31 INFO mapreduce.Job: map 100% reduce 100% 19/08/15 21:31:31 INFO mapreduce.Job: Job job_1562128011754_0026 failed with state FAILED due to: Task failed task_1562128011754_0026_m_000000 Job failed as tasks failed. failedMaps:1 failedReduces:0

19/08/15 21:31:31 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)=53207 Total time spent by all reduces in occupied slots (ms)=0 Total time spent by all map tasks (ms)=7601 Total time spent by all reduce tasks (ms)=0 Total vcore-milliseconds taken by all map tasks=7601 Total vcore-milliseconds taken by all reduce tasks=0 Total megabyte-milliseconds taken by all map tasks=54483968 Total megabyte-milliseconds taken by all reduce tasks=0

Answer 1

You have two nested classes: Map and Reduce. The error says that java was not able to find find them. Most probably the jar /home/nahmed/WordcountSample.jar doesn't contains them. Verify that executing:

 jar -tf  /home/nahmed/WordcountSample.jar

If they were not included in the jar, I think the issue the way you compile.