public double getAverageLoad() {
    int totalLoad = 0;
    int numServers = 0;
    for (ServerMetrics sl : this.onlineServers.values()) {
      numServers++;
      totalLoad += sl.getRegionMetrics().size();
    }
    return numServers == 0 ? 0 : (double) totalLoad / (double) numServers;
  }
Compute the average load across all region servers. Currently, this uses a very naive
computation - just uses the number of regions being served, ignoring stats about number of
requests.
@return the average load
hbase-server/src/main/java/org/apache/hadoop/hbase/master/ServerManager.java