chainScale: Secure Functionality-oriented Scalability for Decentralized Resource Markets

Abstract: Decentralized resource markets are Web 3.0 applications that build open-access platforms for trading digital resources among users without any central management. They promise cost reduction, transparency, and flexible service provision. However, these markets usually have large workload that must be processed in a timely manner, leading to serious scalability problems. Despite the large amount of work on blockchain scalability, existing solutions are ineffective as they do not account for these markets' work models and traffic patterns. We introduce chainScale, a secure hybrid sidechain-sharding solution that aims to boost throughput of decentralized resource markets and reduce their latency and storage footprint. At its core, chainScale leverages dependent sidechains and functionality-oriented workload splitting to parallelize traffic processing by having each market module assigned to a sidechain. Different from sharding, chainScale does not incur any cross-sidechain transactions that tend to be costly. chainScale introduces several techniques, including hierarchical workload sharing that further sub-divides overloaded modules, and weighted miner assignment that assigns miners with vested interest in the system to critical modules' sidechains. Furthermore, chainScale employs sidechain syncing to maintain the mainchain as the single truth of system state, and pruning to discard stale records. Beside analyzing security, we build a proof-of-concept implementation for a distributed file storage market as a use case. Our experiments show that, compared to a single sidechain-based prior solution, chainScale boosts throughput by 4x and reduces confirmation latency by 5x. Also, they show that chainScale outperforms sharding by 2.5x in throughput and 3.5x in latency.