HammerHead: Leader Reputation for Dynamic Scheduling

TL;DR

HammerHead introduces a leader reputation mechanism for DAG-based blockchain consensus, improving fault tolerance and significantly reducing latency and increasing throughput during faults.

Contribution

It presents HammerHead, a novel leader reputation approach that enhances performance and fault resilience in DAG-based blockchain consensus protocols.

Findings

2x latency reduction under faults

40% throughput increase during faults

slight performance gain in faultless settings

Abstract

The need for high throughput and censorship resistance in blockchain technology has led to research on DAG-based consensus. The Sui blockchain protocol uses a variant of the Bullshark consensus algorithm due to its lower latency, but this leader-based protocol causes performance issues when candidate leaders crash. In this paper, we explore the ideas pioneered by Carousel on providing Leader-Utilization and present HammerHead. Unlike Carousel, which is built with a chained and pipelined consensus protocol in mind, HammerHead does not need to worry about chain quality as it is directly provided by the DAG, but needs to make sure that even though validators might commit blocks in different views the safety and liveness is preserved. Our implementation of HammerHead shows a slight performance increase in a faultless setting, and a drastic 2x latency reduction and up to 40% throughput increase when suffering faults (100 validators, 33 faults).