Ladon: High-Performance Multi-BFT Consensus via Dynamic Global Ordering (Extended Version)

2024-09-17

arXiv.org

AI Summary

To address the performance bottleneck in multi-BFT parallel consensus—specifically, global cross-instance block ordering impeded by straggler nodes due to heterogeneous block generation rates—this paper proposes Ladon, a causality-aware, dynamically rank-driven global ordering mechanism. Ladon abandons static global indexing and instead introduces monotonic ranks to decouple block generation from ordering, embedding rank coordination as a pipelined step within the consensus protocol. It employs aggregate signatures to compress rank metadata while preserving causal consistency. The design is compatible with both PBFT and HotStuff. In wide-area network experiments with 128 nodes, under a single-straggler scenario, Ladon-PBFT achieves an 8× throughput improvement and 62% latency reduction; Ladon-HotStuff achieves a 2× throughput gain and 23% latency reduction.

Technology Category

• Search and Optimization: Distributed Search
• Data Mining & Knowledge Management: Scalability, Parallel & Distributed Systems
• Multiagent Systems: Mechanism Design

Application Category

• Security and Privacy: Blockchains and distributed ledgers
• Search and Retrieval-Augmented AI: Web learning to rank, online learning, and counterfactual learning for ranking
• Graph Algorithms and Modeling for the Web: Efficient manipulation of static and dynamic Web-related graphs

Abstract

Multi-BFT consensus runs multiple leader-based consensus instances in parallel, circumventing the leader bottleneck of a single instance. However, it contains an Achilles' heel: the need to globally order output blocks across instances. Deriving this global ordering is challenging because it must cope with different rates at which blocks are produced by instances. Prior Multi-BFT designs assign each block a global index before creation, leading to poor performance. We propose Ladon, a high-performance Multi-BFT protocol that allows varying instance block rates. Our key idea is to order blocks across instances dynamically, which eliminates blocking on slow instances. We achieve dynamic global ordering by assigning monotonic ranks to blocks. We pipeline rank coordination with the consensus process to reduce protocol overhead and combine aggregate signatures with rank information to reduce message complexity. Ladon's dynamic ordering enables blocks to be globally ordered according to their generation, which respects inter-block causality. We implemented and evaluated Ladon by integrating it with both PBFT and HotStuff protocols. Our evaluation shows that Ladon-PBFT (resp., Ladon-HotStuff) improves the peak throughput of the prior art by $approx$8x (resp., 2x) and reduces latency by $approx$62% (resp., 23%), when deployed with one straggling replica (out of 128 replicas) in a WAN setting.

Problem

• Dynamic global ordering of blocks in Multi-BFT consensus.
• Eliminating performance bottlenecks caused by slow instances.
• Improving throughput and latency in distributed systems.

Innovation

• Dynamic global ordering for Multi-BFT consensus
• Pipelined rank coordination reduces protocol overhead
• Aggregate signatures combined with rank information