streaming flow control

Forgive me if I've overlooked documentation on this subject, but I'm trying to understand how to properly configure flow control on streaming interfaces. Usually with Node streams I believe you would set the `highWatermark` option, however it appears that gRPC does not accept that option.

I thought maybe there was a grpc specific configuration that could be set, but after looking through the available options, it wasn't very clear to me if there was and how to use it correctly.

Essentially the issue I have is that I want to temporarily stop buffering results, typically in Node you would use the `pause()` and `resume()` methods to do this, however even if a stream is paused its internal buffer continues to get filled up and if I'm unable to configure the size of said buffer, I start to see increased memory usage.