Hi,
I try to run a Hadoop reduce-side join, then I get the following:
java.lang.NoClassDefFoundError:
org/apache/hadoop/contrib/utils/join/DataJoinMapperBase
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:791)
at
java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
at java.net.URLClassLoader.defineClass(URLClassLoader.java:449)
at java.net.URLClassLoader.access$100(URLClassLoader.java:71)
at java.net.URLClassLoader$1.run(URLClassLoader.java:361)
at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
at java.lang.ClassLoader.loadClass(ClassLoader.java:423)
at java.lang.ClassLoader.loadClass(ClassLoader.java:356)
at DataJoin.run(DataJoin.java:105)
at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:65)
at DataJoin.main(DataJoin.java:119)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:601)
at org.apache.hadoop.util.RunJar.main(RunJar.java:165)
at org.apache.hadoop.mapred.JobShell.run(JobShell.java:54)
at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:65)
at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:79)
at org.apache.hadoop.mapred.JobShell.main(JobShell.java:68)
Caused by: java.lang.ClassNotFoundException:
org.apache.hadoop.contrib.utils.join.DataJoinMapperBase
at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
at java.lang.ClassLoader.loadClass(ClassLoader.java:423)
at java.lang.ClassLoader.loadClass(ClassLoader.java:356)
... 23 more
What's the problem?
The command I use : hadoop jar JoinHadoop.jar DataJoin
/group/asciaa/fst/input_test_join /group/asciaa/fst/out_test_join
The source is from *Hadoop in action*, chapter5, listing 5.3. I use eclipse
to export it as a jar
My Hadoop is 0.19.2
Thanks!
The source code:
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.Text;
import org.apache.hadoop.io.Writable;
import org.apache.hadoop.mapred.FileInputFormat;
import org.apache.hadoop.mapred.FileOutputFormat;
import org.apache.hadoop.mapred.JobClient;
import org.apache.hadoop.mapred.JobConf;
//import org.apache.hadoop.mapred.KeyValueTextInputFormat;
//import org.apache.hadoop.mapred.MapReduceBase;
//import org.apache.hadoop.mapred.Mapper;
//import org.apache.hadoop.mapred.OutputCollector;
//import org.apache.hadoop.mapred.Reducer;
//import org.apache.hadoop.mapred.Reporter;
import org.apache.hadoop.mapred.TextInputFormat;
import org.apache.hadoop.mapred.TextOutputFormat;
import org.apache.hadoop.util.Tool;
import org.apache.hadoop.util.ToolRunner;
import org.apache.hadoop.contrib.utils.join.DataJoinMapperBase;
import org.apache.hadoop.contrib.utils.join.DataJoinReducerBase;
import org.apache.hadoop.contrib.utils.join.TaggedMapOutput;
public class DataJoin extends Configured implements Tool {
public static class MapClass extends DataJoinMapperBase {
protected Text generateInputTag(String inputFile) {
return new Text(inputFile);
}
protected Text generateGroupKey(TaggedMapOutput aRecord) {
String line = ((Text) aRecord.getData()).toString();
String[] tokens = line.split(",");
String groupKey = tokens[0];
return new Text(groupKey);
}
protected TaggedMapOutput generateTaggedMapOutput(Object value) {
TaggedWritable retv = new TaggedWritable((Text) value);
retv.setTag(this.inputTag);
return retv;
}
}
public static class Reduce extends DataJoinReducerBase {
protected TaggedMapOutput combine(Object[] tags, Object[] values) {
if (tags.length < 2) return null;
String joinedStr = "";
for (int i=0; i<values.length; i++) {
if (i > 0) joinedStr += ",";
TaggedWritable tw = (TaggedWritable) values[i];
String line = ((Text) tw.getData()).toString();
String[] tokens = line.split(",", 2);
joinedStr += tokens[1];
}
TaggedWritable retv = new TaggedWritable(new Text(joinedStr));
retv.setTag((Text) tags[0]);
return retv;
}
}
public static class TaggedWritable extends TaggedMapOutput {
private Writable data;
public TaggedWritable(Writable data) {
this.tag = new Text("");
this.data = data;
}
public Writable getData() {
return data;
}
public void write(DataOutput out) throws IOException {
this.tag.write(out);
this.data.write(out);
}
public void readFields(DataInput in) throws IOException {
this.tag.readFields(in);
this.data.readFields(in);
}
}
public int run(String[] args) throws Exception {
Configuration conf = getConf();
JobConf job = new JobConf(conf, DataJoin.class);
Path in = new Path(args[0]);
Path out = new Path(args[1]);
FileInputFormat.setInputPaths(job, in);
FileOutputFormat.setOutputPath(job, out);
job.setJobName("DataJoin");
job.setMapperClass(MapClass.class);
job.setReducerClass(Reduce.class);
job.setInputFormat(TextInputFormat.class);
job.setOutputFormat(TextOutputFormat.class);
job.setOutputKeyClass(Text.class);
job.setOutputValueClass(TaggedWritable.class);
job.set("mapred.textoutputformat.separator", ",");
JobClient.runJob(job);
return 0;
}
public static void main(String[] args) throws Exception {
int res = ToolRunner.run(new Configuration(),
new DataJoin(),
args);
System.exit(res);
}
}
