Asynchronous consensus (atomic broadcast) can ensure safety and liveness without relying on any network synchrony assumption. However, despite recent advances (e.g., HoneyBadgerBFT, Dumbo) that have substantially improved its performance, those randomized protocols still suffer from large latency. On the other hand, deterministic BFT protocols can be very fast, but they cannot have liveness in an asynchronous network.
In this talk, we will present a practical framework of optimistic asynchronous consensus called Bolt-Dumbo Transformer, that combines the best of both. A deterministic fastlane protocol (Bolt) is run most of the time, but when the network gets stuck, a simple "asynchronous pace synchronization" mechanism (Transformer) will allow all nodes to gracefully fallback to a pessimistic path of asynchronous consensus (Dumbo) and then switch back. Our key observation is that with a proper abstraction of the fastlane (Bolt), we can have the simplest Transformer that is just a binary agreement (instead of the cumbersome multi-valued validated agreement as in the literature). We've also done extensive experiments to understand practical performance.
Zoom Participation. See announcement.