Load-aware shedding in stream processing systems

Abstract

Load shedding is a technique employed by stream processing systems to handle unpredictable spikes in the input load whenever available computing resources are not adequately provisioned. A load shedder drops tuples to keep the input load below a critical threshold and thus avoid tuple queuing and system trashing. In this paper we propose Load-Aware Shedding (LAS), a novel load shedding solution that drops tuples with the aim of maintaining queuing times below a tunable threshold. Tuple execution durations are estimated at runtime using efficient sketch data structures. We provide a theoretical analysis proving that LAS is an (ε, δ)-approximation of the optimal online load shedder and show its performance through a practical evaluation based both on simulations and on a running prototype.