public int[] getOrComputeServerWithBestRegionCachedRatio() {
    if (
      regionServerIndexWithBestRegionCachedRatio == null
        || regionIndexServerIndexRegionCachedRatio.isEmpty()
    ) {
      computeRegionServerRegionCacheRatio();
    }
    return regionServerIndexWithBestRegionCachedRatio;
  }
Populate the maps containing information about how much a region is cached on a region server.
hbase-balancer/src/main/java/org/apache/hadoop/hbase/master/balancer/BalancerClusterState.java