A single machine is the simplest use case for Spark. It is also a great way to sanity check your build. In spark/bin, there is a shell script called run-example, which can be used to launch a Spark job. The run-example script takes the name of a Spark class and some arguments. Earlier, we used the run-example script from the /bin directory to calculate the value of Pi. There is a collection of the sample Spark jobs in examples/src/main/scala/org/apache/spark/examples/.
All of the sample programs take the parameter, master (the cluster manager), which can be the URL of a distributed cluster or local[N], where N is the number of threads.
Going back to our run-example script, it invokes the more general bin/spark-submit script. For now, let's stick with the run-example script.
To run GroupByTest locally, try running the following command:
bin/run-example GroupByTest
This line will produce an output like this given here:
14/11/15 06:28:40 INFO SparkContext: Job finished: count at GroupByTest.scala:51, took 0.494519333 s 2000
