@Override
    public int linkedHashMap(int entry) {
      // hashMap += JAVA32_FIELDREF + PRIMITIVES1
      // hashMap.entry += JAVA32_FIELDREF * 2
      return 72 + 32 * entry;
    }
Estimation of memory footprint of object
storage-api/src/java/org/apache/hadoop/hive/ql/util/JavaDataModel.java