Why use HTTP for transport instead of Messagepack or ZMQ? Seems a bit overkill if you are whipping binary data back and forth between services. Protobuf + ZMQ seems a lot more efficient to me.
Absolute throughput or efficiency isn't the goal of most RPC mechanisms, twirp specifically. However I don't think it's underperformant either. It's very easy to reason about, and debug, plays with ELBs well, and most important, gets developers thinking at a Service to Service RPC level instead of about low level stuff.
Fix and optimize throughput for services which actually have those problems.
Messagepack is a serialization format, not a transport. It is an alternative to protobuf or json.
Mostly people use HTTP because there are so many services and components that already support it (load balancers, proxies, sidecars etc), it has well-supported options for authentication, conveys metadata seamlessly through multiple layers, and its overhead isn't an issue for the kind of payloads they are sending.
