Time for action – using Hadoop to calculate Pi

We will now use a sample Hadoop program to calculate the value of Pi. Right now, this is primarily to validate the installation and to show how quickly you can get a MapReduce job to execute. Assuming the HADOOP_HOME/bin directory is in your path, type the following commands:

$ Hadoop jar hadoop/hadoop-examples-1.0.4.jar  pi 4 1000
Number of Maps  = 4
Samples per Map = 1000
Wrote input for Map #0
Wrote input for Map #1
Wrote input for Map #2
Wrote input for Map #3
Starting Job
12/10/26 22:56:11 INFO jvm.JvmMetrics: Initializing JVM Metrics with processName=JobTracker, sessionId=
12/10/26 22:56:11 INFO mapred.FileInputFormat: Total input paths to process : 4
12/10/26 22:56:12 INFO mapred.JobClient: Running job: job_local_0001
12/10/26 22:56:12 INFO mapred.FileInputFormat: Total input paths to process : 4
12/10/26 22:56:12 INFO mapred.MapTask: numReduceTasks: 1
…
12/10/26 22:56:14 INFO mapred.JobClient:  map 100% reduce 100%
12/10/26 22:56:14...