Dispel: Byzantine SMR with Distributed Pipelining
This addresses scaling challenges in blockchain systems for companies seeking high-throughput, fault-tolerant replication, though it appears incremental as it builds on existing SMR approaches.
The paper tackles the problem of scaling Byzantine State Machine Replication (SMR) for blockchains by proposing Dispel, a new SMR that allows nodes to start consensus instances distributively based on local resource detection, resulting in a 12x speedup over HotStuff on 128 nodes and demonstrating robustness under failures.
Byzantine State Machine Replication (SMR) is a long studied topic that received increasing attention recently with the advent of blockchains as companies are trying to scale them to hundreds of nodes. Byzantine SMRs try to increase throughput by either reducing the latency of consensus instances that they run sequentially or by reducing the number of replicas that send messages to others in order to reduce the network usage. Unfortunately, the former approach makes use of resources in burst whereas the latter requires CPU-intensive authentication mechanisms. In this paper, we propose a new Byzantine SMR called Dispel (Distributed Pipeline) that allows any node to distributively start new consensus instances whenever they detect sufficient resources locally. We evaluate the performance of Dispel within a single datacenter and across up to 380 machines over 3 continents by comparing it against four other SMRs. On 128 nodes, Dispel speeds up HotStuff, the Byzantine fault tolerant SMR being integrated within Facebook's blockchain, by more than 12 times. In addition, we also test Dispel under isolated and correlated failures and show that the Dispel distributed design is more robust than HotStuff. Finally, we evaluate Dispel in a cryptocurrency application with Bitcoin transactions and show that this SMR is not the bottleneck.