[brmgb]

> But how does it work?

There clearly is something doing the scheduling and dispatching somewhere in the stack. There will most likely be queues involved and data structures linking receivers and emitters if you are using events. If you use system threads, they might actually be multiple schedulers involved (the OS one and the runtime one).

My advice is to pick up a system book about designing OS which will have a section about scheduling and work from there. Runtime schedulers are not that different.