code: public void close() throws InterruptedException {
          if (reader_instance != null) {
              reader_instance.closeFiles();
          }
          reader_instance = null;
  
          // you can only close a syncmanager, when drums was opened for READ_WRITE
          if (syncManager != null) {
              syncManager.shutdown();
              syncManager.join();
          }
      }
docs: Closes this DRUMS.
  
  @throws InterruptedException