protected final ConcurrentHashMap<String, JobProcess> runningProcessMap = new ConcurrentHashMap<>();

    protected int processDestroyTimeout = 10;

    @PreDestroy
    public void destroy() {
        for (final String sessionId : runningProcessMap.keySet()) {
            if (logger.isInfoEnabled()) {
                logger.info("Stopping process {}", sessionId);
            }

        }
        final String commandDestroyTimeoutStr = fessConfig.getSystemProperty("thumbnail.command.destroy.timeout");
        if (commandDestroyTimeoutStr != null) {
            commandDestroyTimeout = Long.valueOf(commandDestroyTimeoutStr);
        }
    }

    @Override
    public void destroy() {
        destoryTimer.cancel();
        destoryTimer = null;
    }

    @Override

public interface ThumbnailGenerator {

    String getName();

    boolean generate(String thumbnailId, File outputFile);

    boolean isTarget(Map<String, Object> docMap);

    boolean isAvailable();

    void destroy();

    Tuple3<String, String, String> createTask(String path, Map<String, Object> docMap);

  }
  Status Optimize(Cluster* cluster, const GrapplerItem& item,
                  GraphDef* optimized_graph_def) override;

  ~CGraphOptimizer() override {
    if (optimizer_.destroy_func != nullptr) {
      (*optimizer_.destroy_func)(c_optimizer_);
    }
  }

 private:
  TP_Optimizer optimizer_;
  std::string device_type_;
  void* c_optimizer_;
};

public class EmptyGenerator extends BaseThumbnailGenerator {

    @Override
    public boolean generate(final String thumbnailId, final File outputFile) {
        return false;
    }

    @Override
    public void destroy() {
        // nothing
    }

                } catch (final Exception e) {
                    // ignore
                }
            }
            if (currentProcess != null) {
                try {
                    currentProcess.destroy();
                } catch (final Exception e) {
                    // ignore
                }
            }
            currentProcess = null;

        }
    }

public class WebApiFilter implements Filter {

    @Override
    public void init(final FilterConfig filterConfig) throws ServletException {
        // nothing
    }

    @Override
    public void destroy() {
        // nothing
    }

    @Override
    public void doFilter(final ServletRequest request, final ServletResponse response, final FilterChain chain)
            throws IOException, ServletException {

public class HtmlTagBasedGenerator extends BaseThumbnailGenerator {

    private static final Logger logger = LogManager.getLogger(HtmlTagBasedGenerator.class);

    @Override
    public void destroy() {
    }

    @Override
    public Tuple3<String, String, String> createTask(final String path, final Map<String, Object> docMap) {
        final FessConfig fessConfig = ComponentUtil.getFessConfig();

  // clients from directly destroying this object since it may manage its own
  // lifetime through ref counting. Thus clients MUST call Release() in order to
  // destroy an instance of this class.
  virtual void Release() = 0;

  // Creates an operation builder and ties it to this context.
  // The returned object can be used for setting operation's attributes,

        crawlerStatsHelper.begin(key);
        crawlerStatsHelper.record(key, "aaa");
        logger.info(localLogMsg.get());
        assertNull(localLogMsg.get());

        crawlerStatsHelper.destroy();
        logger.info(localLogMsg.get());
        String[] values = localLogMsg.get().split("\t");
        assertEquals(3, values.length);
        assertEquals("url:test", values[0]);