BETASCO: 面向智能合约分片的联盟区块链系统

基于区块链的去中心化应用已在加密数字货币、云存储、物联网等多个领域提供健壮、可信且持久的服务, 然而区块链的吞吐能力难以满足去中心化应用日益增长的性能需求. 分片是当前主流的区块链性能优化技术, 但现有的区块链分片主要面向用户和用户之间的转账交易, 并不完全适用于以智能合约调用交易为主的去中心化应用. 针对此问题, 设计并实现面向智能合约分片的联盟区块链系统BETASCO. BETASCO为每个智能合约提供一个分片作为独立执行环境, 通过基于分布式散列表的合约定位服务将交易路由至目标智能合约所在的分片, 并通过智能合约间的异步调用机制满足跨智能合约的通信和协作需求. BETASCO通过节点虚拟化允许一个节点加入多个分片, 支持同一组节点上多个智能合约的并行执行. 实验结果表明, BETASCO整体吞吐能力可随智能合约数量的增加而线性增长, 且执行单个智能合约的吞吐能力与HyperLedger Fabric相当.

BETASCO: Consortium Blockchain System Based on Smart Contract-oriented Sharding

Blockchain-based decentralized applications have been providing robust, reliable, and durable services in multiple fields, such as encrypted digital currency, cloud storage, and Internet of Things. However, the throughput capacity of blockchain can no longer meet the increasing performance requirements of decentralized applications. Sharding is the current mainstream performance optimization technology for blockchain. Nevertheless, the existing blockchain sharding approaches, mainly focusing on transactions among users, are not always applicable to decentralized applications dominated by the transactions of smart-contract invocation. To solve the above problem, this study designs and implements the consortium blockchain system BETASCO based on smart contract-oriented sharding. BETASCO provides a shard that serves as an independent execution environment for each smart contract, routes transactions to the shards holding the target smart contracts by a contract location service based on the distributed hash table (DHT), and supports communication and collaboration needs across smart contracts by availing the asynchronous invocation mechanism among smart contracts. By virtualizing the nodes, BETASCO allows each node to join multiple shards to support parallel executions of multiple smart contracts on the same set of nodes. The results of experiments show that the overall throughput capacity of BETASCO linearly increases as the number of smart contracts grows, and the throughput capacity for the execution of a single smart contract is comparable to that of HyperLedger Fabric.