Pandemics In Silico: Scaling an Agent-Based Simulation on Realistic Social Contact Networks

TL;DR

This paper introduces Loimos, a scalable parallel agent-based simulation framework that efficiently models epidemic spread on large social contact networks, demonstrated by simulating a COVID-19 outbreak in California in seconds.

Contribution

The paper presents Loimos, a novel hybrid parallel framework for large-scale epidemic simulation using asynchronous runtime, achieving significant speedups and scalability.

Findings

Simulated 200 days of COVID-19 in California in 42 seconds

Achieved 4.6 billion TEPS on 4096 cores

Demonstrated scalability on large core counts

Abstract

Preventing the spread of infectious diseases requires implementing interventions at various levels of government and evaluating the potential impact and efficacy of those preemptive measures. Agent-based modeling can be used for detailed studies of epidemic diffusion and possible interventions. Modeling of epidemic diffusion in large social contact networks requires the use of parallel algorithms and resources. In this work, we present Loimos, a scalable parallel framework for simulating epidemic diffusion. Loimos uses a hybrid of time-stepping and discrete-event simulation to model disease spread, and is implemented on top of an asynchronous, many-task runtime. We demonstrate that Loimos is to able to achieve significant speedups while scaling to large core counts. In particular, Loimos is able to simulate 200 days of a COVID-19 outbreak on a digital twin of California in about 42 seconds, for an average of 4.6 billion traversed edges per second (TEPS), using 4096 cores on Perlmutter at NERSC.