Cost-Effective Stream Join Algorithm on Cloud System

Matrix-based scheme (Join-Matrix) can prefectly support distributed stream joins, especially for arbitrary join predicates, because it guarantees any tuples from two streams to meet with each other. However,the dynamics and unpredictability features of stream require quick actions on scheme changing. Otherwise, they may lead to degradation of system throughputs and increament of processing latency with the waste of system resources, such as CPUs and Memories. Since Join-Matrix model has the fixed processing architecture with replicated data, these kinds of adverseness will be magnified. Therefore, it is urgent to find a solution that preserves advantages of Join-Matrix model and promises a good usage to computation resources when it meets scheme changing. In this paper, we propose a cost-effective stream join algorithm, which ensures the adaptability of Join-Matrix but with lower resources consumption. Specifically, a varietal matrix generation algorithm is proposed to generate an irregular matrix scheme for assigning the minimal number of tasks; a lightweight migration algorithm is designed to ensure state migration at a low cost; a complete load balance process framework is described to guarantee the correctness during the scheme changing. We conduct extensive experiments to compare our method with baseline systems on both benchmarks and real-workloads, and explain the results in detail.