The blockchain brought interesting properties for many practical applications. However, some properties, such as the transaction processing throughput remained limited, especially in Proof-of-Work blockchains. Therefore, several promising directions, such as sharding designs and DAG-based protocols emerged. In this paper, we focus on DAG-based consensus protocols and present a discrete-event simulator for them. Our simulator can simulate realistic blockchain networks created from data of a Bitcoin network, while its network configuration and topology can be customized. The simulated network consists of honest and malicious miners. Malicious miners do not make any attack on consensus itself. Instead, they use a different transaction selection strategy than honest miners (who select transactions randomly) with the intention to earn unfairly more profits than honest miners at the cost of downgrading the protocol performance by duplicate transactions. As a consequence, this harms the performance of some DAG-based protocols (e.g., PHANTOM and GHOSTDAG) in terms of transaction processing throughput, which we demonstrate in our experiments and extend the results of the related work that contains a small-scale network of 10 nodes by the results obtained on a large-scale network with 7000 nodes. Next, we empirically compare different algorithms for the mempool structure, and we propose a composite mempool structure that is memory-efficient and thus convenient for simulations of resource-demanding large-scale networks.

翻译：摘要：区块链为许多实际应用带来了有趣特性。然而，一些特性（例如交易处理吞吐量）仍然受到限制，尤其是在工作量证明区块链中。因此，分片设计和基于有向无环图的协议等若干有前景的方向应运而生。本文聚焦于基于有向无环图的共识协议，并为其提出一种离散事件模拟器。该模拟器能够模拟基于比特币网络数据构建的现实区块链网络，同时其网络配置和拓扑结构可自定义。模拟网络由诚实矿工和恶意矿工组成。恶意矿工不攻击共识本身，而是采用与诚实矿工（随机选择交易）不同的交易选择策略，意图以降低协议性能（通过重复交易）为代价，比诚实矿工获取更多不公平利润。这导致部分基于有向无环图的协议（如PHANTOM和GHOSTDAG）在交易处理吞吐量方面性能下降。我们通过实验证明了这一现象，并将相关工作中包含10个节点的小规模网络结果扩展至7000个节点的大规模网络。此外，我们通过经验性实验比较了内存池结构的不同算法，并提出了一种复合内存池结构，该结构内存高效，适用于资源密集型大规模网络的模拟。