code: public static synchronized void registerUserThread(String service, UserThreadPool userThreadPool) {
          if (userThreadMap == null) {
              userThreadMap = new ConcurrentHashMap<String, UserThreadPool>();
          }
          userThreadMap.put(service, userThreadPool);
      }
docs: 给某个服务分配到独立的线程池
  
  @param service        服务唯一名
  @param userThreadPool 自定义线程池