Egregoros

@david_chisnall I recall microkernels having similar problems with offering flexible scheduling policies, so that research seems like it might pay off in a bunch of directions.

@zwol Not really, microkernels usually have the scheduler in a single component, so flexible policies are easy. The difficulty they have is quite different: they want to account time spent in server A responding for a message from thread X in task B to thread X and task B. Spring had a good solution to this, but without it it’s easy to introduce priority inversion problems.

@david_chisnall I have the impression Spring's solution rests on "doors" being synchronous. If I designed a microkernel it would be strictly asynchronous: all cross-domain invocations "just" queue a message and the *only* blocking operation is "wait for next message". Backpressure is achieved by charging senders for all messages in flight. I *think* this environment could handle priority inheritance by tracking the task priorities of all unacknowledged messages.

@feld @zwol

Beam is designed around the actor model (plus selective receive, which is why two-phase commit isn't too painful in Erlang but also why Erlang is not deadlock-free by construction). So it makes sense that it would look like another actor-model abstraction.