public static QueueBalancer getBalancer(final String executorName, final Configuration conf,
    final List<BlockingQueue<CallRunner>> queues) {
    Preconditions.checkArgument(queues.size() > 0, "Queue size is <= 0, must be at least 1");
    if (queues.size() == 1) {
      return ONE_QUEUE;
    } else {
      Class<?> balancerClass =
        conf.getClass(CALL_QUEUE_QUEUE_BALANCER_CLASS, CALL_QUEUE_QUEUE_BALANCER_CLASS_DEFAULT);
      return (QueueBalancer) ReflectionUtils.newInstance(balancerClass, conf, executorName, queues);
    }
  }
All requests go to the first queue, at index 0
hbase-server/src/main/java/org/apache/hadoop/hbase/ipc/RpcExecutor.java