Issue in running job on Spring-data hadoop

Question

I have created following Mapper and Reducer using Mahout

package mypackage.ItemSimilarity;

import java.io.IOException;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.mahout.math.VarLongWritable;

public class ItemPrefMapper extends
        Mapper<LongWritable, Text, VarLongWritable, VarLongWritable> {

    private static final Pattern NUMBERS = Pattern.compile("(\\d+)");

    @Override
    public void map(LongWritable key, Text value, Context context)
            throws IOException, InterruptedException {
        String line = value.toString();
        Matcher m = NUMBERS.matcher(line);
        m.find();
        VarLongWritable userID = new VarLongWritable(Long.parseLong(m.group()));
        VarLongWritable itemID = new VarLongWritable();
        while (m.find()) {
            itemID.set(Long.parseLong(m.group()));
            context.write(userID, itemID);
        }
    }
}

Reduces class

package mypackage.ItemSimilarity;

import java.io.IOException;

import org.apache.hadoop.mapreduce.Reducer;
import org.apache.mahout.math.RandomAccessSparseVector;
import org.apache.mahout.math.VarLongWritable;
import org.apache.mahout.math.Vector;
import org.apache.mahout.math.VectorWritable;

public class UserVectorReducer
        extends
        Reducer<VarLongWritable, VarLongWritable, VarLongWritable, VectorWritable> {
    @Override
    public void reduce(VarLongWritable userID,
            Iterable<VarLongWritable> itemPrefs, Context context)
            throws IOException, InterruptedException {
        Vector userVector = new RandomAccessSparseVector(Integer.MAX_VALUE, 100);
        for (VarLongWritable itemPref : itemPrefs) {
            userVector.set((int) itemPref.get(), 1.0f);
        }
        context.write(userID, new VectorWritable(userVector));
    }

}

Spring configuration to run this

<job id="mahoutJob" input-path="/home/ubuntu/input/data.txt" output-path="/home/ubuntu/output"
mapper="mypackage.ItemSimilarity.ItemPrefMapper" 
reducer="mypackage.ItemSimilarity.UserVectorReducer" 
jar-by-class="mypackage.ItemSimilarity.ItemPrefMapper"/>

<job-runner id="myjob-runner" pre-action="setupScript"  job-ref="mahoutJob" 
run-at-startup="true"/>

When I run this I got the following error. I have extended the Hadoop mapper class but spring said it is not a mapper class.

java.lang.RuntimeException: class mypackage.ItemSimilarity.ItemPrefMapper not org.apache.hadoop.mapreduce.Mapper at org.apache.hadoop.conf.Configuration.setClass(Configuration.java:931) at org.apache.hadoop.mapreduce.Job.setMapperClass(Job.java:175) at org.springframework.data.hadoop.mapreduce.JobFactoryBean.afterPropertiesSet(JobFactoryBean.java:153) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1571) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1509) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:521) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:458)

Answer 1

Are you sure about your jar-by-class element? Because it should point to something like main method where you instantiate your ApplicationContext instance.

Also, are you sure about your packages name?

com.threepillar.labs.ItemSimilarity.ItemPrefMapper

and

mypackage.ItemSimilarity.ItemPrefMapper