java.lang.NoSuchMethodException: MapReduce.WordCount$MyMapper.<br>()
今日YARNプラットフォームでプログラムをテストしました.wordcount:
実行結果:
長い間探していました:やっとMyMapperクラスとMyReducerクラスの前にstaticを忘れたことに気づきました.それに加えて、プログラムが正しく実行されました.
package MapReduce;
import java.io.IOException;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.mapreduce.Reducer;
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;
import org.apache.hadoop.mapreduce.lib.partition.HashPartitioner;
public class WordCount
{
public static String path1 = "hdfs://hadoop11:9000/dirdata";// HDFS
public static String path2 = "hdfs://hadoop11:9000/worddir";
public static void main(String[] args) throws Exception
{
Configuration conf = new Configuration();
conf.set("fs.defaultFS", "hdfs://hadoop11:9000");
FileSystem fileSystem = FileSystem.get(conf);// HDFS
if(fileSystem.exists(new Path(path2)))
{
fileSystem.delete(new Path(path2), true);
}
Job job = Job.getInstance(conf);
job.setJarByClass(WordCount.class);
FileInputFormat.setInputPaths(job, new Path(path1));
job.setInputFormatClass(TextInputFormat.class);
job.setMapperClass(MyMapper.class);
job.setMapOutputKeyClass(Text.class);
job.setMapOutputValueClass(LongWritable.class);
job.setNumReduceTasks(1);
job.setPartitionerClass(HashPartitioner.class);
job.setReducerClass(MyReducer.class);
job.setOutputKeyClass(Text.class);
job.setOutputValueClass(LongWritable.class);
job.setOutputFormatClass(TextOutputFormat.class);
FileOutputFormat.setOutputPath(job, new Path(path2));
job.waitForCompletion(true);
}
public class MyMapper extends Mapper<LongWritable, Text, Text, LongWritable>
{
protected void map(LongWritable k1, Text v1,Context context)throws IOException, InterruptedException
{
String[] splited = v1.toString().split("\t");
for (String string : splited)
{
context.write(new Text(string),new LongWritable(1L));
}
}
}
public class MyReducer extends Reducer<Text, LongWritable, Text, LongWritable>
{
protected void reduce(Text k2, Iterable<LongWritable> v2s,Context context)throws IOException, InterruptedException
{
long sum = 0L;
for (LongWritable v2 : v2s)
{
sum += v2.get();
}
context.write(k2,new LongWritable(sum));
}
}
}
実行結果:
Error: java.lang.RuntimeException: java.lang.NoSuchMethodException: MapReduce.WordCount$MyMapper.<init>()
at org.apache.hadoop.util.ReflectionUtils.newInstance(ReflectionUtils.java:131)
at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:722)
at org.apache.hadoop.mapred.MapTask.run(MapTask.java:340)
at org.apache.hadoop.mapred.YarnChild$2.run(YarnChild.java:167)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:415)
at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1556)
at org.apache.hadoop.mapred.YarnChild.main(YarnChild.java:162)
Caused by: java.lang.NoSuchMethodException: MapReduce.WordCount$MyMapper.<init>()
at java.lang.Class.getConstructor0(Class.java:2800)
at java.lang.Class.getDeclaredConstructor(Class.java:2043)
at org.apache.hadoop.util.ReflectionUtils.newInstance(ReflectionUtils.java:125)
... 7 more長い間探していました:やっとMyMapperクラスとMyReducerクラスの前にstaticを忘れたことに気づきました.それに加えて、プログラムが正しく実行されました.
package MapReduce;
import java.io.IOException;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.mapreduce.Reducer;
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;
import org.apache.hadoop.mapreduce.lib.partition.HashPartitioner;
public class WordCount
{
public static String path1 = "hdfs://hadoop11:9000/dirdata";// HDFS
public static String path2 = "hdfs://hadoop11:9000/worddir";
public static void main(String[] args) throws Exception
{
Configuration conf = new Configuration();
conf.set("fs.defaultFS", "hdfs://hadoop11:9000");
FileSystem fileSystem = FileSystem.get(conf);// HDFS
if(fileSystem.exists(new Path(path2)))
{
fileSystem.delete(new Path(path2), true);
}
Job job = Job.getInstance(conf);
job.setJarByClass(WordCount.class);
FileInputFormat.setInputPaths(job, new Path(path1));
job.setInputFormatClass(TextInputFormat.class);
job.setMapperClass(MyMapper.class);
job.setMapOutputKeyClass(Text.class);
job.setMapOutputValueClass(LongWritable.class);
job.setNumReduceTasks(1);
job.setPartitionerClass(HashPartitioner.class);
job.setReducerClass(MyReducer.class);
job.setOutputKeyClass(Text.class);
job.setOutputValueClass(LongWritable.class);
job.setOutputFormatClass(TextOutputFormat.class);
FileOutputFormat.setOutputPath(job, new Path(path2));
job.waitForCompletion(true);
}
public static class MyMapper extends Mapper<LongWritable, Text, Text, LongWritable>
{
protected void map(LongWritable k1, Text v1,Context context)throws IOException, InterruptedException
{
String[] splited = v1.toString().split("\t");
for (String string : splited)
{
context.write(new Text(string),new LongWritable(1L));
}
}
}
public static class MyReducer extends Reducer<Text, LongWritable, Text, LongWritable>
{
protected void reduce(Text k2, Iterable<LongWritable> v2s,Context context)throws IOException, InterruptedException
{
long sum = 0L;
for (LongWritable v2 : v2s)
{
sum += v2.get();
}
context.write(k2,new LongWritable(sum));
}
}
}