What version of gRPC and what language are you using?

2.26

What operating system (Linux, Windows,...) and version?

Linux

What runtime / compiler are you using (e.g. python version or version of gcc)

dotnet 3.1

What did you do?

Client

1. makes a unary request to the server.
2. call await response.ResponseHeaderAsync
3. call await response.ResponseAsync

Server

1. call await WriteResponseHeadersAsync()
2. do some heavy processing, then send the response

What did you expect to see?

Client to get the header first
Then after a while get the response.

What did you see instead?

ResponseHeaderAsync doesn't return until the server send the actual response.