ParBlockchain: Leveraging Transaction Parallelism in Permissioned Blockchain Systems

Many existing blockchains do not adequately address all the characteristics of distributed system applications and suffer from serious architectural limitations resulting in performance and confidentiality issues. While recent permissioned blockchain systems, have tried to overcome these limitations, their focus has mainly been on workloads with no-contention, i.e., no conflicting transactions. In this paper, we introduce OXII, a new paradigm for permissioned blockchains to support distributed applications that execute concurrently. OXII is designed for workloads with (different degrees of) contention. We then present ParBlockchain, a permissioned blockchain designed specifically in the OXII paradigm. The evaluation of ParBlockchain using a series of benchmarks reveals that its performance in workloads with any degree of contention is better than the state of the art permissioned blockchain systems.

I. Introduction

A blockchain is a distributed data structure for recording transactions maintained by many nodes without a central authority [12]. In a blockchain, nodes agree on their shared states across a large network of untrusted participants. Blockchain was originally devised for Bitcoin cryptocurrency [28], however, recent systems focus on its unique features such as transparency, provenance, fault-tolerant, and authenticity to support a wide range of distributed applications. Bitcoin and other cryptocurrencies are permissionless blockchains. In a permissionless blockchain, the network is public, and anyone can participate without a specific identity. Many other distributed applications such as supply chain management [23] and healthcare [6], on the other hand, are deployed on permissioned blockchains consisting of a set of known, identified nodes that still do not fully trust each other.