Modern asynchronous programming

I started to take part of asyncio development at ancient times when the library had called Tulip. We made a bunch of libraries under aio-libs umbrella: aiohttp as the most popular asyncio web client and server library, drivers for PostgreSQL, Redis, Kafka, ElasticSearch, Mongo etc. asyncio proved its reliability, and now it is quite famous: thousands of GitHub projects are based on asyncio, very many companies use asyncio as a basement for their infrastructure. The overall design is good but we made several minor mistakes, most of them are fixed by Python 3.6 and 3.7. By the talk, I want to share my asyncio knowledge and my current understanding of best practices learned the hard way.