code: public void setupExecutors() throws ExecutorManagerException {
      final ImmutableSet<Executor> newExecutors = loadExecutors();
      if (newExecutors.isEmpty()) {
        final String error = "No active executors found";
        logger.error(error);
        throw new ExecutorManagerException(error);
      } else {
        this.activeExecutors = newExecutors;
      }
    }
docs: Loads executors. Can be also used to reload executors if there have been changes in the DB.
  
  @throws ExecutorManagerException if no active executors are found or if loading executors
  fails.