A Framework of Large-Scale Peer-to-Peer Learning System

Federated learning (FL) is a distributed machine learning paradigm in which numerous clients train a model dispatched by a central server while retaining the training data locally. Nonetheless, the failure of the central server can disrupt the training framework. Peer-to-peer approaches enhance the robustness of system as all clients directly interact with other clients without a server. However, a downside of these peer-to-peer approaches is their low efficiency. Communication among a large number of clients is significantly costly, and the synchronous learning framework becomes unworkable in the presence of stragglers. In this paper, we propose a semi-asynchronous peer-to-peer learning system (P2PLSys) suitable for large-scale clients. This system features a server that manages all clients but does not participate in model aggregation. The server distributes a partial client list to selected clients that have completed local training for local model aggregation. Subsequently, clients adjust their own models based on staleness and communicate through a secure multi-party computation protocol for secure aggregation. Through our experiments, we demonstrate the effectiveness of P2PLSys for image classification problems, achieving a similar performance level to classical FL algorithms and centralized training.