@Override
      public int compare(FileStatus f1, FileStatus f2) {
        long f1ConsumedSpace = getSpace(f1);
        long f2ConsumedSpace = getSpace(f2);
        return Long.compare(f2ConsumedSpace, f1ConsumedSpace);
      }
Sort the given list in (descending) order of the space each element takes
@param dirs the list to sort, element in it should be directory (not file)
hbase-server/src/main/java/org/apache/hadoop/hbase/master/cleaner/CleanerChore.java