//== queue
//System.out.println("maxNumHGInQueue=" + maxNumHGInQueue);
BlockingQueue<HGAndReferences> queue = new ArrayBlockingQueue<HGAndReferences>(maxNumHGInQueue);
//== producer
HGProducer producer = new HGProducer(hgFactory, queue, numThreads, numSentence);
//== consumers
List<GradientConsumer> consumers = new ArrayList<GradientConsumer>();
for(int i=0; i<numThreads; i++){