We study the problem of load balancing in distributed stream processing engines, which is exacerbated in the presence of skew. We introduce Partial Key Grouping (PKG), a new stream partitioning scheme that adapts the classical "power of two choices" to a distributed streaming setting by leveraging two novel techniques: key splitting and local load estimation. In so doing, it achieves better load balancing than key grouping while being more scalable than shuffle grouping. We test PKG on several large datasets, both real-world and synthetic. Compared to standard hashing, PKG reduces the load imbalance by up to several orders of magnitude, and often achieves nearly-perfect load balance. This result translates into an improvement of up to 175% in throughput and up to 45% in latency when deployed on a real Storm cluster. PKG has been integrated in Apache Storm v0.10.
@article{arxiv.1510.07623,
title = {Partial Key Grouping: Load-Balanced Partitioning of Distributed Streams},
author = {Muhammad Anis Uddin Nasir and Gianmarco De Francisci Morales and David Garcia-Soriano and Nicolas Kourtellis and Marco Serafini},
journal= {arXiv preprint arXiv:1510.07623},
year = {2015}
}
Comments
14 pages. arXiv admin note: substantial text overlap with arXiv:1504.00788