Every conversation, since episode one.

Hernán Rivas Acosta's first Erlang game server, a football game for Cartoon Network, reached 50,000 concurrent players on one machine. The BEAM didn't stop it there. The OS file descriptor limit did, and the team chose not to raise it. The Java option they had considered would have managed a few thousand.

In 2017, Davide Bettio created AtomVM to run Erlang, Elixir and Gleam code on embedded devices with just a few kilobytes of memory. Fast forward to today, and Giacomo Cavalieri of the Gleam core team has built tooling that flashes a Gleam project onto a board with a single command.

Every secure connection made from an Erlang, Elixir, or Gleam application runs through code she wrote. Most developers have never heard her name.

Brex runs on Elixir. Klarna runs on Erlang. Mastercard is believed to use it. And most of the community that builds on these systems watches them with PromEx - a library written by today's guest.

Part one established that Erlang scales. Part two is about what comes after - keeping a codebase that large healthy for years, when most engineers arrive having never written Erlang before.

Everyone quotes WhatsApp when the topic of Erlang and scale comes up. Fewer people know what it actually looks like from the inside - what was hard, what was never hard, and what the team spent their time on once the concurrency stopped being the problem.