Cross-chain transaction processing is pivotal to blockchain interoperability, enabling coordinated state transitions across multiple blockchains to support increasingly complexdecentralized applications(dApps). However, existing atomicity-preserving mechanisms, predominantly based ontwo-phase commit(2PC) protocols, are hindered by sequential coordination, prolonged state locking, and high susceptibility to cascading aborts. These limitations severely degrade throughput and latency under contention, undermining practical deployability. This paper proposes Furion, a novel cross-chain transaction processing mechanism that achieves both atomicity and efficiency. Furion introduces the multi-future exploration, a new execution paradigm that explicitly materializes multiple possible futures of cross-chain states via multi-versioning. By speculatively executing transactions across feasible state evolutions, Furion eliminates blocking on unresolved dependencies and fundamentally avoids cascading aborts. To further unlock concurrency in the finalization phase, Furion employs preemptive voting, which allows local transactions to cast commit or abort votes early when their outcomes are invariant across all state versions. Experimental evaluations demonstrate that Furion significantly outperforms state-of-the-art systems, achieving substantially higher throughput, lower latency, and markedly reduced abort rates under skewed and highly contended workloads.

Cross-chain Decentralized Applications (dApps) are increasingly popular for their ability to handle complex tasks across various blockchains, extending beyond simple asset transfers or swaps. However, ensuring all dependent transactions execute correctly together, known as complete atomicity, remains a challenge. Existing works provide financial atomicity, protecting against monetary loss, but lack the ability to ensure correctness for complex tasks. In this paper, we introduce Avalon, a transaction execution framework for cross-chain dApps that guarantees complete atomicity for the first time. Avalon achieves this by introducing multiple state layers above the native one to cache state transitions, allowing for efficient management of these state transitions. Most notably, for concurrent cross-chain transactions, Avalon resolves not only intra-chain conflicts but also addresses potential inconsistencies between blockchains via a novel state synchronization protocol, enabling serializable cross-chain execution. We implement Avalon using smart contracts in Cosmos ecosystem and evaluate its commitment performance, demonstrating acceptable latency and gas consumption even under conflict cases.

Increasingly popular decentralized applications (dApps) with complex application logic incur significant overhead for executing smart contract transactions, which greatly limits public blockchain performance. Pre-executing transactions off the critical path can mitigate substantial I/O and computation costs during execution. However, pre-execution does not yield any state transitions, rendering the system state inconsistent with actual execution. This inconsistency can lead to deviations in pre-execution paths when processing smart contracts with multiple state-related branches, thus diminishing pre-execution effectiveness. In this paper, we develop Seer, a novel public blockchain execution engine that incorporates fine-grained branch prediction to fully exploit pre-execution effectiveness. Seer predicts state-related branches using a two-level prediction approach, reducing inconsistent execution paths more efficiently than executing all possible branches. To enable effective reuse of pre-execution results, Seer employs checkpoint-based fast-path execution, enhancing transaction execution for both successful and unsuccessful predictions. Evaluations with realistic blockchain workloads demonstrate that Seer delivers an average of 27.7× transaction-level speedup and an overall 20.6× speedup in the execution phase over vanilla Ethereum, outperforming existing blockchain execution acceleration solutions.