public int getRegionSizeMB(int region) {
    Deque<BalancerRegionLoad> load = regionLoads[region];
    // This means regions have no actual data on disk
    if (load == null) {
      return 0;
    }
    return regionLoads[region].getLast().getStorefileSizeMB();
  }
Returns the size in MB from the most recent RegionLoad for region
hbase-balancer/src/main/java/org/apache/hadoop/hbase/master/balancer/BalancerClusterState.java