They're more like coroutines, but they can be safely pre-empted because Erlang has very little mutable data. Erlang's scheduler also takes dataflow (e.g. which

They're more like coroutines, but they can be safely pre-empted because Erlang has very little mutable data. Erlang's scheduler also takes dataflow (e.g. which processes have new messages to process?) into account, so some kinds of overhead are O(active processes) rather than O(processes).