Rate types for stream programs

Abstract

Abstract. We introduce RATE TYPES, a novel type system to reason about and optimize data-intensive programs. Built around stream languages, RATE TYPES performs static quantitative reasoning about stream rates -the frequency of data items in a stream being consumed, processed, and produced -a critical performance characteristic previously addressed by numerous experimental approaches but few foundational efforts. Even though streams are fundamentally dynamic, we find two essential concepts of stream rate control -throughput ratio and natural rate -are intimately related to the program structure itself and can be effectively reasoned about by a type system. RATE TYPES is proven sound over a time-aware and parallelism-aware operational semantics. The strong soundness result tolerates arbitrary schedules, and does not require any synchronization between stream filters. We further demonstrate the applications of RATE TYPES in energy-efficient computing and CPU allocation on multi-core architectures.