@Override
  public void onConfigurationChange(Configuration conf) {
    float originSlop = slop;
    float originOverallSlop = overallSlop;
    loadConf(conf);
    LOG.info(
      "Update configuration of SimpleLoadBalancer, previous slop is {},"
        + " current slop is {}, previous overallSlop is {}, current overallSlop is {}",
      originSlop, slop, originOverallSlop, overallSlop);
  }
Pass RegionStates and allow balancer to set the current cluster load.
hbase-balancer/src/main/java/org/apache/hadoop/hbase/master/balancer/SimpleLoadBalancer.java