Java 未设置作业 jar 文件。在 Hadoop 中可能找不到用户类
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时间：2020-08-13 08:23:03 来源:igfitidea点击:
No job jar file set. User classes may not be found in Hadoop
提问by lucifer
I am trying to run a MR wordcount job.but i am getting No job jar file set set.i am posting the stacktrace can anyone help me?
我正在尝试运行 MR wordcount 作业。但我没有得到作业 jar 文件集。我正在发布堆栈跟踪，有人可以帮助我吗？
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.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)
and i am running this command
我正在运行这个命令
hadoop jar wordcount.jar org.gamma.WordCount /user/jeet/getty/gettysburg.txt /user/jeet/getty1/out
And this is my wordcount class
这是我的 wordcount 课
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);
}
}
采纳答案by jtravaglini
You are submitting the Job before telling the job which JAR class corresponds to it. It's pretty clear in your error message:
在告诉作业对应哪个 JAR 类之前提交作业。在您的错误消息中很清楚：
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 your driver, and it will work:
交换驱动程序的最后两行，它将起作用：
job.setJarByClass(WordCount.class);
job.waitForCompletion(true);
