# Revisiting consensus protocols through wait-free parallelization

## TL;DR

This paper introduces a wait-free parallelization method for consensus protocols that enhances performance and robustness by running multiple instances in parallel, reducing load and mitigating malicious influence.

## Contribution

It proposes a protocol-agnostic, wait-free parallelization approach for primary-backup consensus protocols, improving performance and security.

## Key findings

- Reduces load on individual consensus instances.
- Mitigates impact of malicious primaries.
- Enhances overall system robustness.

## Abstract

The recent surge of blockchain systems has renewed the interest in traditional Byzantine fault-tolerant consensus protocols. Many such consensus protocols have a primary-backup design in which an assigned replica, the primary, is responsible for coordinating the consensus protocol. Although the primary-backup design leads to relatively simple and high performance consensus protocols, it places an unreasonable burden on a good primary and allows malicious primaries to substantially affect the system performance. In this paper, we propose a protocol-agnostic approach to improve the design of primary backup consensus protocols. At the core of our approach is a novel wait-free approach of running several instances of the underlying consensus protocol in parallel. To yield a high performance parallelized design, we present coordination-free techniques to order operations across parallel instances, deal with instance failures, and assign clients to specific instances. Consequently, the design we present is able to reduce the load on individual instances and primaries, while also reducing the adverse effects of any malicious replicas.