Source: have worked there for over 5 years.
https://blog.twitch.tv/en/2015/12/18/twitch-engineering-an-i...
The history is basically:
- v1: IRC API to process scoped servers (Python backend, haxe front end)
- kept API as we migrated backed to go (via a terrible course through nodejs); this version allowed all participants to be in a room together (ie cross process servers).
- once most of background was on go we migrated the front end (can’t remember to what)
- backend then got revved a lot (a specialized team was convened to work on chat infrastructure full time)
I left in 2017, no idea what has happened since.
Well, one known issue was a netsplit [1]. But it did work most of the time.