Histogram sort with sampling

Abstract

To minimize data movement, state-of-the-art parallel sorting algorithms use techniques based on sampling and histogramming to partition keys prior to redistribution. Sampling enables partitioning to be done using a representative subset of the keys, while histogramming enables evaluation and iterative improvement of a given partition. We introduce Histogram sort with sampling (HSS), which combines sampling and iterative histogramming to find high-quality partitions with minimal data movement and high practical performance. Compared to the best known (recently introduced) algorithm for finding these partitions, our algorithm requires a factor of Θ(log(p)/ log log(p)) less communication, and substantially less when compared to standard variants of Sample sort and Histogram sort. We provide a distributed-memory implementation of the proposed algorithm, compare its performance to two existing implementations, and provide a brief application study showing benefit of the new algorithm.