public void start() {
    if (coordinatorStreamConsumer != null) {
      LOG.debug("Starting coordinator system stream consumer.");
      coordinatorStreamConsumer.start();
    }
    if (coordinatorStreamProducer != null) {
      LOG.debug("Starting coordinator system stream producer.");
      coordinatorStreamProducer.start();
    }
  }
Starts the underlying coordinator stream producer and consumer.
samza-core/src/main/java/org/apache/samza/coordinator/stream/CoordinatorStreamManager.java