MVCX: An Efficient Multi-Version-Based Concurrency Control Scheme for Cross-Chain Smart Contract Transactions

As blockchain applications become increasingly specialized and fragmented, cross-chain smart contract transactions are essential for platform interoperability. The inherent, significant confirmation delays of these transactions, in serial execution mode, lead to substantial degradation of system performance. To address this issue, existing solutions typically employ Two-Phase Locking (2PL) and Optimistic Concurrency Control (OCC) to support concurrent transaction processing. 2PL-based approaches result in transaction blocking due to continuous resource locking, which substantially degrades system performance. OCC-based approaches frequently encounter transaction aborts and rollbacks due to resource modification conflicts, causing resource wastage. To overcome these challenges, this paper proposes MVCX, a novel concurrency control solution that supports lock-free parallel execution of cross-chain smart contract transactions without sacrificing atomicity. MVCX adopts a speculative execution model driven by multi-version management, combined with conflict detection and re-execution of conflicting transactions to eliminate locking operations. Additionally, MVCX introduces Composite Transaction Units (CTUs) and a depth-first construction (DFC) algorithm, along with a deferred commit mechanism, ensuring that transactions are committed in accordance with their dependency order to maintain correctness and atomicity. Experimental results using SmallBank and YCSB workloads under varying data contention levels demonstrate that MVCX reduces transaction latency by 65% and abort rates by 55% on average, compared to AtomCI and Spectrum.