HTTP/2 response completed before its request

Here’s an HTTP/2 scenario that we ran into
<https://github.com/square/okhttp/issues/929> with OkHttp…

   1. Our client POSTs a large image. In this case, large means “larger
   than the configured initial window size”.
   2. The server reads our request headers and sends a response (headers +
   body) immediately. The response includes an END_STREAM flag, indicating
   that no further response body frames are expected.
   3. The client continues to upload the request.
   4. The client upload exhausts the window and stalls.
   5. The server never sends a RST_STREAM or WINDOW_UPDATE frame, so the
   client eventually times out.

What’s interesting…

The server sent its complete response before the request completed.
Thinking in HTTP/1.1, I hadn’t anticipated this possibility. The response
code was 500, which suggests a crash in the server somewhere. Should the
spec mention this possibility? What are the obligations on the client in
this case? What would it mean for a server to return a 200 response to a
POST-in-progress?

The error also caused the server to lose our stream. This is a partition in
the CAP sense, and timeouts are the client’s failsafe to detect this.
HTTP/2 can suffer partitions in the application layer!
​