Data races are a subset of all race conditions. We don't claim that it's impossible to wait on a network message that never arrives, of course!

However, Pony makes a messaging order guarantee that's much stronger than is typical for the actor model. It guarantees causal messaging. That is, any message that is a "cause" of another message (i.e. was sent or received by an actor prior to the message in question) is guaranteed to arrive before the "effect" if they have the same destination.

That guarantee is achieved with no runtime cost, which is pretty fun.

Pony still allows unbounded non-determinism, of course, but causal messaging gives a very comfortable guarantee to the programmer.