Bitcoin is the first fully-decentralized permissionless blockchain protocol to achieve a high level of security, but at the expense of poor throughput and latency. Scaling the performance of Bitcoin has a been a major recent direction of research. One successful direction of work has involved replacing proof of work (PoW) by proof of stake (PoS). Proposals to scale the performance in the PoW setting itself have focused mostly on parallelizing the mining process, scaling throughput; the few proposals to improve latency have either sacrificed throughput or the latency guarantees involve large constants rendering it practically useless. Our first contribution is to design a new PoW blockchain Prism++ that has provably low latency and high throughput; the design retains the parallel-chain approach espoused in Prism but invents a new confirmation rule to infer the permanency of a block by combining information across the parallel chains. We show security at the level of Bitcoin with very small confirmation latency (a small constant factor of block interarrival time). A key aspect to scaling the performance is to use a large number of parallel chains, which puts significant strain on the system. Our second contribution is the design and evaluation of a practical system to efficiently manage the memory, computation, and I/O imperatives of a large number of parallel chains. Our implementation of Prism++ achieves a throughput of over 80,000 transactions per second and confirmation latency of tens of seconds on networks of up to 900 EC2 Virtual Machines.

翻译：比特币是首个实现高安全性、完全去中心化、无需许可的区块链协议，但以低吞吐量和高延迟为代价。提升比特币性能已成为近期研究的主要方向。一项成功的研究路径是用权益证明取代工作量证明。而针对工作量证明场景下的性能扩展方案，主要聚焦于并行化挖矿过程以提升吞吐量；少数改进延迟的方案要么牺牲吞吐量，要么其延迟保证涉及大常数，导致实际应用无效。我们的第一项贡献是设计新型工作量证明区块链Prism++，该方案具有可证明的低延迟和高吞吐量；设计继承了Prism倡导的并行链方法，但提出了一种新的确认规则，通过跨并行链的信息聚合推断区块的永久性。我们证明其安全性达到比特币水平，且确认延迟极低（仅为区块到达间隔时间的小常数倍）。性能扩展的关键在于使用大量并行链，这给系统带来显著压力。我们的第二项贡献是设计并评估了一个实用系统，可高效管理大量并行链所需的内存、计算及I/O资源。我们的Prism++实现方案在多达900个EC2虚拟机构成的网络上，实现了超过每秒80,000笔交易的吞吐量及数十秒的确认延迟。