public static String formatTimeDiff(long finishTime, long startTime){
    long timeDiff = finishTime - startTime;
    return formatTime(timeDiff);
  }
Given a finish and start time in long milliseconds, returns a
String in the format Xhrs, Ymins, Z sec, for the time difference between two times.
If finish time comes before start time then negative values of X, Y and Z will return.

@param finishTime finish time
@param startTime start time
common/src/java/org/apache/hive/common/util/HiveStringUtils.java