public static int getDefaultNotificationInterval(Configuration hconf) {
    int notificationInterval;
    Integer expInterval = Integer.decode(hconf.get("mapred.tasktracker.expiry.interval"));

    if (expInterval != null) {
      notificationInterval = expInterval.intValue() / 2;
    } else {
      // 5 minutes
      notificationInterval = 5 * 60 * 1000;
    }
    return notificationInterval;
  }
Gets the default notification interval to send progress updates to the tracker. Useful for
operators that may not output data for a while.

@param hconf
@return the interval in milliseconds
ql/src/java/org/apache/hadoop/hive/ql/exec/Utilities.java