CAF - the C++ Actor Framework for Scalable and Resource-Efficient Applications

The actor model of computation has gained significant popularity over the last decade. Its high level of abstraction combined with its flexibility and efficiency makes it appealing for large applications in concurrent and distributed regimes. In this paper, we report on our work of designing and building CAF, the "C++ Actor Framework". CAF targets at providing an extremely scalable native environment for building high-performance concurrent applications and distributed systems. Based on our previous library tt libcppa, CAF significantly extends its scopes of application and operation, as well as the range of scalability. The particular contributions of this paper are threefold. First we present the design and implementation of a type-safe messaging interface for actors that rules out a category of runtime errors and facilitates robust software design. Second we introduce a runtime inspection shell as a first building block for convenient debugging of distributed actors. Finally we enhance the scheduling facilities and improve scaling up to high numbers of concurrent processors. Extensive performance evaluations indicate ideal runtime behaviour for up to 64 cores at very low memory footprint. In these tests, CAF clearly outperforms competing actor environments.