[HADOOP] Mapreduce 작업이 실행되고 예외가 있습니다.

Mapreduce 작업이 실행되고 예외가 있습니다.

내 코드는 다음과 같습니다.

import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import java.util.Iterator;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.conf.Configured;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.DoubleWritable;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.io.WritableComparable;
import org.apache.hadoop.io.WritableUtils;
import org.apache.hadoop.mapred.*;
import org.apache.hadoop.util.Tool;
import org.apache.hadoop.util.ToolRunner;

public class SecondarySort extends Configured implements Tool{

public static void main(String[] args) {
    try {
        ToolRunner.run(new Configuration(), new SecondarySort(), args);
    } catch (Exception e) {
        e.printStackTrace();
    }
}

static class KeyPartitioner implements Partitioner<StockKey, DoubleWritable> {

    @Override
    public int getPartition(StockKey arg0, DoubleWritable arg1, int arg2) {

        int partition = arg0.name.hashCode() % arg2;

        return partition;
    }

    @Override
    public void configure(JobConf job) {
    }

}


static class StockKey implements WritableComparable<StockKey> {

    String name;
    Long timestamp;

    public StockKey() {

    }

    StockKey(String name, Long timestamp){
        this.name = name;
        this.timestamp = timestamp;
    }

    @Override
    public void readFields(DataInput arg0) throws IOException {
        name = WritableUtils.readString(arg0);
        timestamp = arg0.readLong();
    }

    @Override
    public void write(DataOutput arg0) throws IOException {
        WritableUtils.writeString(arg0, name);
        arg0.writeLong(timestamp);
    }

    @Override
    public int compareTo(StockKey arg0) {
        int result = 0;

        result = name.compareToIgnoreCase(arg0.name);

        if(result == 0)
            result = timestamp.compareTo(arg0.timestamp);   

        return result;
    }

    public String toString() {
        String outputString = name+","+timestamp;
        return outputString;
    }
}


static class StockReducer implements Reducer<StockKey, DoubleWritable, Text, Text>{

    public void reduce(StockKey key, Iterator<DoubleWritable> value, Outp      
OutputCollector<Text, Text> context, Reporter reporter) 
                throws IOException {

        Text k = new Text(key.toString());

        while(value.hasNext()) {

            Double v = value.next().get();
            Text t = new Text(v.toString());

            context.collect(k, t);          
        }
    }

    @Override
    public void configure(JobConf job) {
        // TODO Auto-generated method stub

    }

    @Override
    public void close() throws IOException {
        // TODO Auto-generated method stub

    }
}


static class StockMapper implements Mapper<LongWritable, Text, StockKey, 
DoubleWritable> {

    public void map(LongWritable offset, Text value, OutputCollector<StockKey, 
DoubleWritable> context, Reporter reporter) 
                throws IOException {

        String[] values = value.toString().split(",");
        StockKey key = new StockKey(values[0].trim(), 
Long.parseLong(values[1].trim()));
        DoubleWritable val = new 
DoubleWritable(Double.parseDouble(values[2].trim()));


            context.collect(key, val);

    }

    @Override
    public void configure(JobConf job) {
        // TODO Auto-generated method stub

    }

    @Override
    public void close() throws IOException {
        // TODO Auto-generated method stub

    }

}

@SuppressWarnings("unchecked")
@Override
public int run(String[] arg) throws Exception {

    JobConf conf = new JobConf(getConf(), SecondarySort.class);
    conf.setJobName(SecondarySort.class.getName());

    conf.setJarByClass(SecondarySort.class);

    conf.setInputFormat(TextInputFormat.class);
    conf.setOutputFormat(TextOutputFormat.class);

    conf.setMapOutputKeyClass(StockKey.class);
    conf.setMapOutputValueClass(Text.class);

    conf.setPartitionerClass((Class<? extends Partitioner<StockKey, 
DoubleWritable>>) KeyPartitioner.class);

    conf.setMapperClass((Class<? extends Mapper<LongWritable, Text, StockKey, 
DoubleWritable>>) StockMapper.class);
    conf.setReducerClass((Class<? extends Reducer<StockKey, DoubleWritable, 
Text, Text>>) StockReducer.class);

    FileInputFormat.addInputPath(conf, new Path(arg[0]));
    FileOutputFormat.setOutputPath(conf, new Path(arg[1]));

    JobClient.runJob(conf);

    return 0;
}

}

예외는 다음과 같습니다.

java.io.IOException: Type mismatch in value from map: expected 
org.apache.hadoop.io.Text, recieved org.apache.hadoop.io.DoubleWritable
    at org.apache.hadoop.mapred.MapTask$MapOutputBuffer.collect(MapTask.java:876)
    at org.apache.hadoop.mapred.MapTask$OldOutputCollector.collect(MapTask.java:499)
    at SecondarySort$StockMapper.map(SecondarySort.java:135)
    at SecondarySort$StockMapper.map(SecondarySort.java:1)
    at org.apache.hadoop.mapred.MapRunner.run(MapRunner.java:50)
    at org.apache.hadoop.mapred.MapTask.runOldMapper(MapTask.java:391)
    at org.apache.hadoop.mapred.MapTask.run(MapTask.java:325)
    at org.apache.hadoop.mapred.Child$4.run(Child.java:270)
    at java.security.AccessController.doPrivileged(Native Method)
    at javax.security.auth.Subject.doAs(Subject.java:396)
    at     
org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1127)
    at org.apache.hadoop.mapred.Child.main(Child.java:264)


12/07/13 03:22:32 INFO mapred.JobClient: Task Id :   
attempt_201207130314_0002_m_000001_2, Status : FAILED

java.io.IOException: Type mismatch in value from map: expected 
org.apache.hadoop.io.Text, recieved org.apache.hadoop.io.DoubleWritable
    at org.apache.hadoop.mapred.MapTask$MapOutputBuffer.collect(MapTask.java:876)
    at org.apache.hadoop.mapred.MapTask$OldOutputCollector.collect(MapTask.java:499)
    at SecondarySort$StockMapper.map(SecondarySort.java:135)
    at SecondarySort$StockMapper.map(SecondarySort.java:1)
    at org.apache.hadoop.mapred.MapRunner.run(MapRunner.java:50)
    at org.apache.hadoop.mapred.MapTask.runOldMapper(MapTask.java:391)
    at org.apache.hadoop.mapred.MapTask.run(MapTask.java:325)
    at org.apache.hadoop.mapred.Child$4.run(Child.java:270)
    at java.security.AccessController.doPrivileged(Native Method)
    at javax.security.auth.Subject.doAs(Subject.java:396)
    at 
org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1127)
    at org.apache.hadoop.mapred.Child.main(Child.java:264)

해결법

1. ==============================

   1.이 코드에는 여러 가지 잠재적 인 문제가있어 다음과 같은 원인이 될 수 있습니다.

   이 코드에는 여러 가지 잠재적 인 문제가있어 다음과 같은 원인이 될 수 있습니다.

   context.collect 호출 주위에서 try / catch 블록을 제거하고 작업을 다시 실행하는 것이 좋습니다 (또는 맵 작업의 로그를 확인하고 스택 추적이 있는지 확인).

from https://stackoverflow.com/questions/11447736/mapreduce-job-runs-and-there-is-an-exception by cc-by-sa and MIT license