hadoop utilities : Cluster Status

gistfile1.java

package sujee;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.conf.Configured;
import org.apache.hadoop.mapred.ClusterStatus;
import org.apache.hadoop.mapred.JobClient;
import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.util.Tool;
import org.apache.hadoop.util.ToolRunner;

/*
compile into a jar and execute:
     hadoop jar a.jar sujee.TestCluster

output:
number of task trackers: 1
maximum map tasks : 3
currently running map tasks : 0

*/

public class TestCluster extends Configured implements Tool
{
    public static void main(String[] args) throws Exception
    {
        int result = ToolRunner.run(new Configuration(), new TestCluster(), args);
        System.exit(result);
    }

    @Override
    public int run(String[] arg0) throws Exception
    {
        JobConf dummyJob = new JobConf(new Configuration(), TestCluster.class);
        JobClient jobClient = new JobClient(dummyJob);
        ClusterStatus clusterStatus = jobClient.getClusterStatus();
        System.out.println("number of task trackers: " + clusterStatus.getTaskTrackers());
        System.out.println("maximum map tasks : " + clusterStatus.getMaxMapTasks());
        System.out.println("currently running map tasks : " + clusterStatus.getMapTasks());
        return 0;
    }
}