Job jar file is not set. User classes may not be found in Hadoop… here is a solution to the problem.
Job jar file is not set. User classes may not be found in Hadoop
I’m trying to run the MR wordcount job. But I didn’t set up the job jar fileset. I’m posting a stack trace, can someone help me?
14/01/27 16:52:26 WARN mapred. JobClient: Use GenericOptionsParser for parsing the arguments. Applications should implement Tool for the same.
14/01/27 16:52:26 WARN mapred. JobClient: No job jar file set. User classes may not be found. See JobConf(Class) or JobConf#setJar(String).
14/01/27 16:52:26 INFO input. FileInputFormat: Total input paths to process : 1
14/01/27 16:52:26 INFO util. NativeCodeLoader: Loaded the native-hadoop library
14/01/27 16:52:26 WARN snappy. LoadSnappy: Snappy native library not loaded
14/01/27 16:52:27 INFO mapred. JobClient: Running job: job_201401271610_0002
14/01/27 16:52:28 INFO mapred. JobClient: map 0% reduce 0%
14/01/27 16:52:35 INFO mapred. JobClient: Task Id : attempt_201401271610_0002_m_000000_0, Status : FAILED
java.lang.RuntimeException: java.lang.ClassNotFoundException: org.gamma.WordCount$Map
at org.apache.hadoop.conf.Configuration.getClass(Configuration.java:849)
at org.apache.hadoop.mapreduce.JobContext.getMapperClass(JobContext.java:199)
at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:719)
at org.apache.hadoop.mapred.MapTask.run(MapTask.java:370)
at org.apache.hadoop.mapred.Child$4.run(Child.java:255)
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:1149)
I’m running this command
hadoop jar wordcount.jar org.gamma.WordCount /user/jeet/getty/gettysburg.txt /user/jeet/getty1/out
This is my word count class
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;
public class WordCount {
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);
}
}
}
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();
Job job = new Job(conf, "WordCount");
job.setOutputKeyClass(Text.class);
job.setOutputValueClass(IntWritable.class);
job.setMapperClass(Map.class);
job.setReducerClass(Reduce.class);
job.setInputFormatClass(TextInputFormat.class);
job.setOutputFormatClass(TextOutputFormat.class);
FileInputFormat.addInputPath(job, new Path(args[0]));
FileOutputFormat.setOutputPath(job, new Path(args[1]));
job.waitForCompletion(true);
job.setJarByClass(WordCount.class);
}
}
Solution
You are submitting the job before telling the job which JAR class corresponds to it. Very clear in your error message:
14/01/27 16:52:26 WARN mapred. JobClient: No job jar file set. User classes may not be found. See JobConf(Class) or JobConf#setJar(String).
Swap the last two lines of the driver and it will work:
job.setJarByClass(WordCount.class);
job.waitForCompletion(true);