core/src/main/java/com/twitter/elephantbird/util/HdfsUtils.java
public static long getDirectorySize(Path path, FileSystem fs) throws IOException {
    ContentSummary cs = fs.getContentSummary(path);
    return cs.getLength();
  }
public static long getDirectorySize(Path path, FileSystem fs) throws IOException {
    ContentSummary cs = fs.getContentSummary(path);
    return cs.getLength();
  }
Calculates the total size of all the contents of a directory,
including the contents of all of its subdirectories.
Does not include the size of directories themselves
(which are 0 in HDFS but may not be 0 on local file systems)

@param path path to recursively walk
@param fs FileSystem for this path
@return size of the directory's contents in bytes
@throws IOException