@InterfaceAudience.Private
  static Map<byte[], Integer> createFamilyBlockSizeMap(Configuration conf) {
    Map<byte[], String> stringMap = createFamilyConfValueMap(conf, BLOCK_SIZE_FAMILIES_CONF_KEY);
    Map<byte[], Integer> blockSizeMap = new TreeMap<>(Bytes.BYTES_COMPARATOR);
    for (Map.Entry<byte[], String> e : stringMap.entrySet()) {
      Integer blockSize = Integer.parseInt(e.getValue());
      blockSizeMap.put(e.getKey(), blockSize);
    }
    return blockSizeMap;
  }
Runs inside the task to deserialize column family to block size map from the configuration.
@param conf to read the serialized values from
@return a map from column family to the configured block size
hbase-mapreduce/src/main/java/org/apache/hadoop/hbase/mapreduce/HFileOutputFormat2.java