def forcibly_stop_workers
      return unless @workers.size > 0
      GRPC.logger.info("forcibly terminating #{@workers.size} worker(s)")
      @workers.each do |t|
        next unless t.alive?
        begin
          t.exit
        rescue StandardError => e
          GRPC.logger.warn('error while terminating a worker')
          GRPC.logger.warn(e)
        end
      end
    end
def forcibly_stop_workers
      return unless @workers.size > 0
      GRPC.logger.info("forcibly terminating #{@workers.size} worker(s)")
      @workers.each do |t|
        next unless t.alive?
        begin
          t.exit
        rescue StandardError => e
          GRPC.logger.warn('error while terminating a worker')
          GRPC.logger.warn(e)
        end
      end
    end
Forcibly shutdown any threads that are still alive.