Scaling Nakamoto Consensus to Thousands of Transactions per Second

TL;DR

This paper introduces Conflux, a scalable blockchain system that uses a DAG-based consensus protocol to achieve high transaction throughput of up to 6400 transactions per second, confirmed within minutes.

Contribution

Conflux presents a novel DAG-based consensus protocol that allows for high throughput and fast confirmation times without discarding blocks, improving scalability of blockchain systems.

Findings

Achieves 6400 transactions per second on Amazon EC2 clusters.

Confirms transactions within 4.5-7.4 minutes.

Consensus protocol is not the throughput bottleneck.

Abstract

This paper presents Conflux, a fast, scalable and decentralized blockchain system that optimistically process concurrent blocks without discarding any as forks. The Conflux consensus protocol represents relationships between blocks as a direct acyclic graph and achieves consensus on a total order of the blocks. Conflux then, from the block order, deterministically derives a transaction total order as the blockchain ledger. We evaluated Conflux on Amazon EC2 clusters with up to 20k full nodes. Conflux achieves a transaction throughput of 5.76GB/h while confirming transactions in 4.5-7.4 minutes. The throughput is equivalent to 6400 transactions per second for typical Bitcoin transactions. Our results also indicate that when running Conflux, the consensus protocol is no longer the throughput bottleneck. The bottleneck is instead at the processing capability of individual nodes.