# Engineering Massively Parallel MST Algorithms

## TL;DR

This paper presents scalable distributed-memory algorithms for minimum spanning trees, including a variant of Boruvka's algorithm and a parallel Filter-Boruvka, achieving significant speedups on large core counts.

## Contribution

It introduces new scalable distributed MST algorithms, including a contracting approach and a parallel Filter-Boruvka, outperforming previous methods.

## Key findings

- Algorithms scale up to 65,536 cores
- Up to 800 times faster than prior algorithms
- Effective for graphs with poor locality and high degree

## Abstract

We develop and extensively evaluate highly scalable distributed-memory algorithms for computing minimum spanning trees (MSTs). At the heart of our solutions is a scalable variant of Boruvka's algorithm. For partitioned graphs with many local edges, we improve this with an effective form of contracting local parts of the graph during a preprocessing step. We also adapt the filtering concept of the best practical sequential algorithm to develop a massively parallel Filter-Boruvka algorithm that is very useful for graphs with poor locality and high average degree. Our experiments indicate that our algorithms scale well up to at least 65 536 cores and are up to 800 times faster than previous distributed MST algorithms.