@Override
    public int linkedHashMap(int entry) {
      // hashMap += JAVA64_FIELDREF + PRIMITIVES1
      // hashMap.entry += JAVA64_FIELDREF * 2
      return 128 + 60 * entry;
    }
Estimation of memory footprint of object
storage-api/src/java/org/apache/hadoop/hive/ql/util/JavaDataModel.java