Sharding scales throughput by splitting blockchain nodes into parallel groups. However, different shards' independent and random scheduling for cross-shard transactions results in numerous conflicts and aborts, since cross-shard transactions from different shards may access the same account. A deterministic ordering can eliminate conflicts by determining a global order for transactions before processing, as proved in the database field. Unfortunately, due to the intertwining of the Byzantine environment and information isolation among shards, there is no trusted party able to predetermine such an order for cross-shard transactions. To tackle this challenge, this paper proposes Prophet, a conflict-free sharding blockchain based on Byzantine-tolerant deterministic ordering. It first depends on untrusted self-organizing coalitions of nodes from different shards to pre-execute cross-shard transactions for prerequisite information about ordering. It then determines a trusted global order based on stateless ordering and post-verification for pre-executed results, through shard cooperation. Following the order, the shards thus orderly execute and commit transactions without conflicts. Prophet orchestrates the pre-execution, ordering, and execution processes in the sharding consensus for minimal overhead. We rigorously prove the determinism and serializability of transactions under the Byzantine and sharded environment. An evaluation of our prototype shows that Prophet improves the throughput by $3.11\times$ and achieves nearly no aborts on 1 million Ethereum transactions compared with state-of-the-art sharding.

翻译：摘要：分片通过将区块链节点划分为并行组来提升吞吐量。然而，不同分片对跨片交易的独立随机调度会导致大量冲突与中止，因为来自不同分片的跨片交易可能访问同一账户。如数据库领域所证明，确定性排序可通过在处理前确定交易的全局顺序来消除冲突。但不幸的是，由于拜占庭环境与分片间信息隔离的相互交织，不存在可信方能够为跨片交易预定义此类顺序。为应对这一挑战，本文提出Prophet——一种基于拜占庭容错确定性排序的无冲突分片区块链。它首先依赖来自不同分片的不可信自组织节点联盟，对跨片交易进行预执行以获取排序所需的前提信息；随后通过分片协作，基于无状态排序与预执行结果的后验证，确定可信全局顺序。各分片据此顺序无冲突地有序执行并提交交易。Prophet将预执行、排序与执行流程编排至分片共识中，以最小化开销。我们严格证明了交易在拜占庭与分片环境下的确定性与可串行化性。原型评估表明，与最先进分片方案相比，Prophet在百万级以太坊交易场景中吞吐量提升3.11倍，且几乎无交易中止。