Right, but the problem is that with async communication, you don't need a synchronous ack handshake.
Instead you can pipeline both messages: `[hello][are you coming to lunch with us?]`, and that's more convenient and efficient for the receiver and sender.
The problem that TFA is referring to is that context switching is very expensive for the receiver, so without pipelining, the receiver pays a huge cost just to send back the ack and then again to finally reply to the payload once it is sent. The receiver is asking that you send all messages; it prefers to buffer them.
Instead you can pipeline both messages: `[hello][are you coming to lunch with us?]`, and that's more convenient and efficient for the receiver and sender.
The problem that TFA is referring to is that context switching is very expensive for the receiver, so without pipelining, the receiver pays a huge cost just to send back the ack and then again to finally reply to the payload once it is sent. The receiver is asking that you send all messages; it prefers to buffer them.