Sample application for dynamic partitioning

In this section, we will take a detailed look at an example application that illustrates the use of dynamic partitioning of an operator. It uses an input operator that generates random numbers and outputs them to a DevNull library operator (which, as the name suggests, simply discards them). The input operator starts out with two partitions; after some tuples have been processed, a dynamic repartition is triggered via the StatsListener interface discussed above to increase the number of partitions to four. The source code is available atthe following link: https://github.com/apache/apex-malhar/tree/master/examples/dynamic-partition.

The populateDAG() method is, as expected, very simple:

@Override 
public void populateDAG(DAG dag, Configuration conf) 
{ 
  Gen gen         = dag.addOperator("gen",     Gen.class); 
  DevNull devNull = dag.addOperator("devNull", DevNull.class); 
  dag.addStream("data", gen.out, devNull.data); 
} 

The interesting code...