if (executorService == null) {
                int numThreads = ComponentUtil.getFessConfig().getRankFusionThreadsAsInteger();
                if (numThreads <= 0) {
                    numThreads = Runtime.getRuntime().availableProcessors() * 3 / 2 + 1;
                }
                if (logger.isDebugEnabled()) {
                    logger.debug("Initializing executor service with {} threads", numThreads);
                }

                @Override
                public void run() {
                    destroyContainer();
                }

            };
            Runtime.getRuntime().addShutdownHook(shutdownCallback);

            commandThread = new Thread(() -> {
                try (BufferedReader reader = new BufferedReader(new InputStreamReader(System.in))) {
                    String command;

                            + "'. Value must be positive.");
                }

                int procs = Runtime.getRuntime().availableProcessors();
                int threads = (int) (coreMultiplier * procs);
                return threads == 0 ? 1 : threads;
            } else {

 *           // some other action.  For now we will just exit.
 *           System.exit(1);
 *         }
 *       },
 *       MoreExecutors.directExecutor());
 *
 *     Runtime.getRuntime().addShutdownHook(new Thread() {
 *       public void run() {
 *         // Give the services 5 seconds to stop to ensure that we are responsive to shutdown
 *         // requests.
 *         try {

 *           // some other action.  For now we will just exit.
 *           System.exit(1);
 *         }
 *       },
 *       MoreExecutors.directExecutor());
 *
 *     Runtime.getRuntime().addShutdownHook(new Thread() {
 *       public void run() {
 *         // Give the services 5 seconds to stop to ensure that we are responsive to shutdown
 *         // requests.
 *         try {

                  // We're shutting down anyway, so just ignore.
                }
              }));
    }

    @VisibleForTesting
    void addShutdownHook(Thread hook) {
      Runtime.getRuntime().addShutdownHook(hook);
    }
  }

  @J2ktIncompatible
  @GwtIncompatible // TODO
  private static void useDaemonThreadFactory(ThreadPoolExecutor executor) {
    executor.setThreadFactory(

                            + "'. Value must be positive.");
                }

                int procs = Runtime.getRuntime().availableProcessors();
                int threads = (int) (coreMultiplier * procs);
                return threads == 0 ? 1 : threads;
            } else {

        append(buf, "unloaded", () -> classes.getUnloadedClassCount());
        buf.append("},");
        append(buf, "uptime", () -> jvmStats.getUptime().getMillis());
        buf.append("},");
    }

    private void appendProcessStats(final StringBuilder buf) {
        buf.append("\"process\":{");

        jvmClassesObj.total_loaded = classes.getTotalLoadedClassCount();
        jvmClassesObj.unloaded = classes.getUnloadedClassCount();
        jvmObj.uptime = jvmStats.getUptime().getMillis();
        return jvmObj;
    }

    private ProcessObj getProcessObj() {
        final ProcessObj processObj = new ProcessObj();
        final ProcessProbe processProbe = ProcessProbe.getInstance();