X-Shard : Optimistic Cross-Shard Transaction Processing for Sharding-Based Blockchains

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Original languageEnglish
Pages (from-to)548-559
Journal / PublicationIEEE Transactions on Parallel and Distributed Systems
Issue number4
Online published1 Feb 2024
Publication statusPublished - Apr 2024


Recent advances in cryptocurrencies have sparked significant interest in blockchain technology. However, scalability issues remain a major challenge for wide adoption of blockchains. Sharding is a promising approach to scale blockchains, but existing sharding-based blockchains fail to achieve expected performance gains due to limitations in cross-shard transaction processing. In this paper, we propose X-shard, a blockchain system that optimizes cross-shard transaction processing, achieving high effective throughput and low processing latency. First, we allocate transactions to shards based on historical transaction patterns to minimize cross-shard transactions. Second, we take an optimistic strategy to process cross-shard transactions in parallel as sub-transactions within input shards, thereby accelerating transaction processing. Finally, we employ a cross-shard commit protocol with threshold signatures to reduce communication overhead. We implement and deploy X-shard on Amazon EC2 clusters. Experimental results validate our theoretical analysis and show that as the number of shards increases, X-shard achieves nearly linear scaling in effective throughput and decreases in transaction processing latency. © 2024 IEEE.

Research Area(s)

  • Blockchain scalability, distributed system, optimistic concurrency control, sharding