code: public void shutdownNow() {
      logger.warn("Shutting down FlowRunnerManager now...");
      if (this.azkabanProps.getBoolean(ConfigurationKeys.AZKABAN_POLL_MODEL, false)) {
        this.pollingService.shutdown();
      }
      this.executorService.shutdownNow();
      this.triggerManager.shutdown();
    }
docs: This attempts shuts down the flow runner immediately (unsafe). This doesn't wait for jobs to
  finish but interrupts all threads.