code: public AbstractNettyChannel newChannel() throws InterruptedException {
          ChannelFuture channelFuture = bootstrap.connect(remoteAddress).sync();
          Channel channel = channelFuture.channel();
          return this.callBack == null ? new SyncNettyChannel(this, channel) : new AsyncNettyChannel(this, channel);
      }
docs: 只有单线程执行该方法，不用加同步