thread “main” java.lang.NoClassDefFoundError : Exception in org/apache/hadoop/hbase/HBaseConfiguration
I’m using Hadoop 1.0.3 and HBase 0.94.22. I’m trying to run a mapper program to read values from an Hbase table and output them to a file. I get the following error:
Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/hadoop/hbase/HBaseConfiguration
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:340)
at org.apache.hadoop.util.RunJar.main(RunJar.java:149)
Caused by: java.lang.ClassNotFoundException: org.apache.hadoop.hbase.HBaseConfiguration
at java.net.URLClassLoader$1.run(URLClassLoader.java:372)
at java.net.URLClassLoader$1.run(URLClassLoader.java:361)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:360)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
The code is as follows
import java.io.IOException;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hbase.HBaseConfiguration;
import org.apache.hadoop.hbase.client.Result;
import org.apache.hadoop.hbase.client.Scan;
import org.apache.hadoop.hbase.filter.FirstKeyOnlyFilter;
import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
import org.apache.hadoop.hbase.mapreduce.TableMapReduceUtil;
import org.apache.hadoop.hbase.mapreduce.TableMapper;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
public class Test {
static class TestMapper extends TableMapper<Text, IntWritable> {
private static final IntWritable one = new IntWritable(1);
public void map(ImmutableBytesWritable row, Result value, Context context) throws IOException, InterruptedException
{
ImmutableBytesWritable userkey = new ImmutableBytesWritable(row.get(), 0 , Bytes.SIZEOF_INT);
String key =Bytes.toString(userkey.get());
context.write(new Text(key), one);
}
}
public static void main(String[] args) throws Exception {
HBaseConfiguration conf = new HBaseConfiguration();
Job job = new Job(conf, "hbase_freqcounter");
job.setJarByClass(Test.class);
Scan scan = new Scan();
FileOutputFormat.setOutputPath(job, new Path(args[0]));
String columns = "data";
scan.addFamily(Bytes.toBytes(columns));
scan.setFilter(new FirstKeyOnlyFilter());
TableMapReduceUtil.initTableMapperJob("test",scan, TestMapper.class, Text.class, IntWritable.class, job);
job.setOutputKeyClass(Text.class);
job.setOutputValueClass(IntWritable.class);
System.exit(job.waitForCompletion(true)?0:1);
}
}
I export the above code
to a jar file and run the above code on the command line with the following command.
Hadoop jar/home/testdb.jar test
where test is the folder where mapper results should be written.
I checked some other links like Caused by: java.lang.ClassNotFoundException: org.apache.zookeeper.KeeperException It is recommended to include the zookeeper file in the classpath, but when creating the project in Eclipse, I have included the zookeeper file in the lib directory of hbase. The file I’m including is zookeeper-3.4.5.jar. Ans also visited this link HBase – java.lang.NoClassDefFoundError in java, but I’m using the mapper class to get values from hbase tables instead of getting values from any client API. I know I made a mistake somewhere, can you guys help me?
I
noticed another strange thing when I removed the first line in the main function except “HBaseConfiguration conf = new HBaseConfiguration(); “, then export the code to a jar file and try to compile that jar file for hadoop jar test.jar I still get the same error. It looks like I’m not defining the conf variable correctly, or there’s something wrong with my environment.
Solution
I
got a fix for the issue where I didn’t add the hbase classpath in the hadoop-env.sh file. Here’s what I added to make things work.
$ export HADOOP_CLASSPATH=$HBASE_HOME/hbase-0.94.22.jar:\
$HBASE_HOME/hbase-0.94.22-test.jar:\
$HBASE_HOME/conf:\
${HBASE_HOME}/lib/zookeeper-3.4.5.jar:\
${HBASE_HOME}/lib/protobuf-java-2.4.0a.jar:\
${HBASE_HOME}/lib/guava-11.0.2.jar
