Support for asynchronous serial communications

[teauxfu]

This issue is for collecting information regarding implementing support for single-threaded asynchronous serial communications via pyserial-ascynio.

As it currently stands the IO delays are relatively small (30-50 ms for a single, successful write/read pair), and there seems to not be a great deal of benefit to doing this. I may implement it anyway, just for the sake of practice, but it's currently lowest-priority.

A combination of multithreading via concurrent.futures.ThreadPoolExecutor with queue.Queue has been sufficient for my own purposes when communicating with multiple pumps while also doing other things (running UI, logging to files, etc.).
If anyone encounters limitations with this approach or is aware of a neat alternative I would love to hear about it!

pySerial itself only has experimental support for use with threading.

Packages

• pyserial-asyncio only has support for OSX, Linux, and BSD
  There seems to be experimental support for Windows
• aioserial may be an option
  sounds like this just uses multithreading internally
• asyncserial-py only supports Python 3.6 😞
  seems abandoned

Helpful links / resources / examples

• Zach Mitchell's wonderful post on using pyserial-asyncio fantastic tutorial, probably the easiest pattern to implement
• Ajit Samudrala on asyncio, threading, and multiprocessing
• Lei Mao on asyncio, threading, and multiprocessing
• RealPython article/tutorial on async (general)
• RealPython article/tutorial on asyncio specifically
• Educative blogpost on concurrency/asyncio
• SO thread asyncio vs threads performance