One of my favorite talks is by Rick Reed about scaling Erlang at WhatsApp. What an absolute savage. He flies through an articulate and in-depth curriculum on system performance and bottleneck mitigation.
I remember that year. I was giving a talk at EF during the same time slot but the schedule originally had me in the large room and they had a much smaller one.
When the news of the acquisition hit, everyone wanted to see the WhatsApp talk. The organizers knew this so we swapped rooms. So, I started my talk by asking if anyone in the room was here for the WhatsApp talk and told them they could quietly leave and I wouldn't mind and a bunch of people got up.
Heheh. I don't blame them. I didn't really like my talk and Rick Reed is very good at what he does and the talk is no exception.
I've written our data processing layer and our event orchestration layer as basically an actor oriented system, with push/pull systems in a couple of key places where it makes sense. It's incredible what you can do with strong isolated infrastructure in terms of performance, security, reliability, and quality.
I know nothing about Erlang, but I do know high-volume systems. Needing 550 beefy servers to handle all that load is - in my mind - not that impressive.
The talk is called "That's 'Billion' with a 'B'" and makes for a great lunchtime watch: https://www.youtube.com/watch?v=c12cYAUTXXs