code: final void shutdown() {
          _enabled = false;
          _ignoredSegs.clear();
          
          if(_executor != null && !_executor.isShutdown()) {
              try {
                  _executor.shutdown();
                  _log.info("shutdown");
              } catch (Exception e) {
                  _log.warn("shutdown abort", e);
              }
              
              try {
                  _executor.awaitTermination(_shutdownTimeout, TimeUnit.SECONDS);
              } catch (Exception e) {
                  _log.warn("shutdown abort", e);
              }
              
              if(_segTarget != null) {
                  try {
                      _updateManager.endUpdate(_segTarget);
                  } catch (Exception e) {
                      _log.warn("shutdown abort", e);
                  }
              }
          }
          
          _executor = null;
          _state = State.DONE;
      }
docs: Note that this method is called only by SimpleDataArray.