Orbit: A Dynamic Account Allocation Mechanism in Sharding Blockchain System

The account allocation mechanism is a crucial component affecting the performance of sharding blockchain systems. A well-designed account allocation mechanism must reduce the number of cross-shard transactions while balancing the workload across shards. State-of-the-art mechanisms, which are semi-static, typically adjust account partitions based on historical transactions at regular intervals. However, in real-world applications, unpredictable new scenarios in historical transactions or sudden workload changes can impact shard performance. These existing mechanisms can neither foresee such scenarios to avoid cross-shard transactions nor dynamically adjust account partitions to improve workload issues, leading to suboptimal performance until the next re-allocation. To this end, we propose Orbit, a dynamic account allocation mechanism based on the pending transactions in the pool. Orbit can promptly detect new situations and changes in pending transactions and provide updated allocation strategies. Moreover, through its off-chain scheduling mechanism, Orbit can deploy these strategies before transaction packaging to enhance shard performance. Experimental results show that compared to the state-of-the-art allocation mechanisms, Orbit improves throughput by 2.02 times, reduces cross-shard transactions to 11.9%, and achieves a more balanced shard workload. Additionally, Orbit excels in various other aspects, including latency, transaction queue size, and bandwidth overhead, outperforming the state-of-the-art mechanisms.