code: public synchronized void cancelHeartBeat() {
  		if(threadsNeedingHeartBeat > 0) {
  			threadsNeedingHeartBeat--;
  		} else {
  			Exception e = new Exception("Dummy");
  			e.fillInStackTrace();
  			LOG.warn("extra call to cancelHeartBeat", e);
  		}
  	}
docs: inform the background thread that this heartbeat request is not needed. This must be called at some point after
  each {@link #needHeartBeat()} request.