code: @Override
  	public synchronized void close() throws IOException {
  		// cancel synchronization
  		try {
  			if (syncTask != null) {
  				syncTask.cancel();
  			}
  			sync();
  			unmapFile();
  		} finally {
  			super.close();
  		}
  	}
docs: Closes the underlying RRD file.
  
  @throws IOException Thrown in case of I/O error