Programming Parallelism with Futures in Lustre

Best paper award.International audienceEfficiently distributing synchronous programs is a challenging and long-standing subject. This paper introduces the use of futures in a Lustre-like language, giving the programmer control over the expression of parallelism. In the synchronous model where computations are considered instantaneous, futures increase expressiveness by decoupling the beginning from the end of a computation. Through a number of examples, we show how to desynchronize long computations and implement parallel patterns such as fork-join, pipelining and data parallelism. The proposed extension preserves the main static properties of the base language, including static resource bounds and the absence of deadlock, livelock and races. Moreover, we prove that adding or removing futures preserves the underlying synchronous semantics