private static int calcMruCap(int metricsSize) {
    return (int) Math.ceil(metricsSize / MRU_LOAD_FACTOR) + 1;
  }
Calculates the mru cache capacity from the metrics size
hbase-hadoop-compat/src/main/java/org/apache/hadoop/hbase/master/balancer/MetricsStochasticBalancerSourceImpl.java