BrokerChain: A Blockchain Sharding Protocol by Exploiting Broker Accounts

TL;DR

BrokerChain is a novel blockchain sharding protocol that uses broker accounts and fine-grained state partitioning to balance workloads and reduce cross-shard transactions, improving performance and scalability.

Contribution

It introduces a new cross-shard protocol leveraging broker accounts and state segmentation to address workload imbalance and cross-shard transaction reduction.

Findings

Outperforms baselines in throughput and latency

Achieves better workload balance across shards

Reduces cross-shard transaction quantity

Abstract

State-of-the-art blockchain sharding solutions such as Monoxide, can cause severely imbalanced distribution of transaction (TX) workloads across all blockchain shards due to the deployment policy of their accounts. Imbalanced TX distributions then produce hot shards, in which the cross-shard TXs may experience an unlimited confirmation latency. Thus, how to address the hot-shard issue and how to reduce crossshard TXs become significant challenges of blockchain sharding. Through reviewing the related studies, we find that a crossshard TX protocol that can achieve workload balance among all shards and simultaneously reduce the quantity of crossshard TXs is still absent from the literature. To this end, we propose BrokerChain, which is a cross-shard blockchain protocol dedicated to account-based state sharding. Essentially, BrokerChain exploits fine-grained state partition and account segmentation. We also elaborate on how BrokerChain handles cross-shard TXs through broker accounts. The security issues and other properties of BrokerChain are analyzed rigorously. Finally, we conduct comprehensive evaluations using an opensource blockchain sharding prototype named BlockEmulator. The evaluation results show that BrokerChain outperforms other baselines in terms of transaction throughput, transaction confirmation latency, the queue size of the transaction pool, and workload balance.