Reproduction of issue #1375 in tonic.

Here I have made 3 APIs that return a stream.

1. futures::mpsc to return the stream (the solution in the issue)
2. async_stream to return the stream my attempt at an alternative to tokio's mpsc that didn't work
3. tokio's mpsc channel
4. async-channels mpmc bounded channel

You can either run the server and the client separately or run them both at once. There are 3 binaries server, client, both which do these respectively.

Running as both lets you match up the timestamps more easily but if going into the hyper logs the extra noise from both server and client in the same process may be a pain to debug hence the 3 options.

The batching issue can be observed with all channels apart from futures::mpsc with a capacity of 0.