Asynchronous Distributed-Memory Parallel Algorithms for Influence Maximization

Influence maximization (IM) is the problem of finding the k most influential nodes in a graph. We propose distributed-memory parallel algorithms for the two main kernels of a state-of-the-art implementation of one IM algorithm, influence maximization via martingales (IMM). The baseline relies on a bulk-synchronous parallel approach and uses replication to reduce communication and achieve approximate load balance, at the cost of synchronization and high memory requirements. By contrast, our method fully distributes the data, thereby improving memory scalability, and uses fine-grained asynchronous parallelism to improve network utilization and the cost of doing more communication. We show our design and implementation can achieve up to 29.6x speedup over the MPI-based state-of-the-art on synthetic and real-world network graphs. Moreover, ours is the first implementation that can run IMM to find influencers in the 'twitter' graph (41M nodes and 1.4B edges) in 200 seconds using 8K CPU cores of NERSC Perlmutter supercomputer.