Teleport messaging for distributed stream programs

In this paper, we develop a new language construct to address one of the pitfalls of parallel programming: precise handling of events across parallel components. The construct, termed teleport messaging, uses data dependences between components to provide a common notion of time in a parallel system. Our work is done in the context of the Synchronous Dataflow (SDF) model, in which computation is expressed as a graph of independent components (or actors) that communicate in regular patterns over data channels. We leverage the static properties of SDF to compute a stream dependence function, sdep, that compactly describes the ordering constraints between actor executions. Teleport messaging utilizes sdep to provide powerful and precise event handling. For example, an actor A can specify that an event should be processed by a downstream actor B as soon as B sees the “effects ” of the current execution of A. We argue that teleport messaging improves readability and robustness over existing practices. We have implemented messaging as part of the StreamIt compiler, with a backend for a cluster of workstations. As teleport messaging exposes optimization opportunities to the compiler, it also results in a 49 % performance improvement for a software radio benchmark