We present the design of an alternative runtime system for improved scalability and reduced latency in actor applications called Agner. Agner provides higher scalability by allowing the application developer to specify the network overlay used at runtime without changing application semantics, thereby specializing the network communication patterns to the application. Agner reduces message latency through a combination of three predominately automatic optimizations: parallelism, named channels, and affinitized scheduling. We implement a prototype of Agner in Erlang and demonstrate that Agner achieves up to an order of magnitude increase in the number of nodes the system can scale to through runtime overlay selection, up to a 34.96x increase in throughput, and up to a 13.4x reduction in latency over Distributed Erlang.
