I struggled with the concept of mutexes a lot when I first started out (beam does have them, but not commonly used). I often asked my coworker “but what about race conditions? How does it solve for them?” He said something along the lines of “they didn’t solve them, they just don’t exist.”

That’s a bit tongue in cheek because of course they can still exist. However, GenServer makes it possible to solve many classes of problem that would be an issue and need mutexes in other languages. I’d say a large reason that mutexes are used in other languages just aren’t needed. The reason for this is that a GenServer can process one message at a time.

In this case, I’d probably have a GenServer that knows about all users connected (via some sort of registration mechanism such as a Registry), and then it shuffles and passes a message to each when 5 join.

This becomes harder when distributed because you need all 5 players to be on the same GenServer. This is easiest when they’re on the same Beam Node. There are techniques to solve this distributed, still GenServer without mutexes, but requires a bit more mechanism.

Also, welcome to the Elixir forum!