@Override
  public synchronized void cancel(boolean mayInterruptIfRunning) {
    super.cancel(mayInterruptIfRunning);
    for (Thread t : this.threads) {
      t.interrupt();
    }
  }
Check new configuration and update settings if value changed
@param conf The new configuration
@return true if any configuration for HFileCleaner changes, false if no change
hbase-server/src/main/java/org/apache/hadoop/hbase/master/cleaner/HFileCleaner.java