code: public void processEvent(ContentEvent event, int counter) {
  		if (this.piInstances == null || this.piInstances.size() < this.getParallelism())
  			throw new IllegalStateException("ThreadsWorkerProcessingItem(s) need to be setup before process any event (i.e. in ThreadsTopology.start()).");
  		
  		ThreadsProcessingItemInstance piInstance = this.piInstances.get(counter);
  		ThreadsEventRunnable runnable = new ThreadsEventRunnable(piInstance, event);
  		ThreadsEngine.getThreadWithIndex(piInstance.getThreadIndex()).submit(runnable);
  	}
docs: /*
  Process the received event.