code: @Override
      public void rebalance() throws InterruptedException {
          if (state.get() != NodeState.Fresh && !waitInProgress.get()) {
              balancingPolicy.rebalance();
          }
      }
docs: Initiates a cluster rebalance. If smart balancing is enabled, the target load
  is set to (total cluster load / node count), where "load" is determined by the
  sum of all work unit meters in the cluster. If smart balancing is disabled,
  the target load is set to (# of work items / node count).