Mosaic: Client-driven Account Allocation Framework in Sharded Blockchains

2025-04-15

AI Summary

Existing sharded blockchains rely on miners to perform global optimization for account allocation, requiring each miner to store the complete ledger—entailing prohibitive storage, communication, and computational overhead. This work proposes the first client-driven, lightweight distributed account allocation framework: clients autonomously execute lightweight local optimization (e.g., using the built-in Pilot algorithm) based solely on their local state and submit migration requests exclusively via the beacon chain—eliminating miner involvement in global decision-making. This paradigm fundamentally alleviates both miner incentive misalignment and resource overhead, while supporting arbitrary client-side optimization algorithms. Experiments on a real Ethereum dataset demonstrate that per-account input size is compressed from 1.44 GB to 228.66 bytes, and computation time is reduced by four orders of magnitude. Cross-shard transaction rate increases only marginally (~5%), and system throughput remains at 98% of baseline.

Technology Category

• Search and Optimization: Distributed Search
• Data Mining & Knowledge Management: Scalability, Parallel & Distributed Systems
• Multiagent Systems: Mechanism Design

Application Category

• Security and Privacy: Blockchains and distributed ledgers
• Economics, Online Markets and Human Computation: Economic aspects of blockchain and cryptocurrencies
• Responsible Web: Algorithmic accountability and transparency on the web

Abstract

Recent account allocation studies in sharded blockchains are typically miner-driven, requiring miners to perform global optimizations for all accounts to enhance system-wide performance. This forces each miner to maintain a complete copy of the entire ledger, resulting in significant storage, communication, and computation overhead. In this work, we explore an alternative research direction by proposing Mosaic, the first client-driven framework for distributed, lightweight local optimization. Rather than relying on miners to allocate all accounts, Mosaic enables clients to independently execute a local algorithm to determine their residing shards. Clients can submit migration requests to a beacon chain when relocation is necessary. Mosaic naturally addresses key limitations of miner-driven approaches, including the lack of miner incentives and the significant overhead. While clients are flexible to adopt any algorithm for shard allocation, we design and implement a reference algorithm, Pilot, to guide them. Clients execute Pilot to maximize their own benefits, such as reduced transaction fees and confirmation latency. On a real-world Ethereum dataset, we implement and evaluate Pilot against state-of-the-art miner-driven global optimization solutions. The results demonstrate that Mosaic significantly enhances computational efficiency, achieving a four-order-of-magnitude reduction in computation time, with the reduced input data size from 1.44 GB to an average of 228.66 bytes per account. Despite these efficiency gains, Pilot introduces only about a 5% increase in the cross-shard ratio and maintains approximately 98% of the system throughput, demonstrating a minimal trade-off in overall effectiveness.

Problem

• Client-driven account allocation in sharded blockchains
• Eliminates miner-driven global optimization overhead
• Reduces storage and computation costs significantly

Innovation

• Client-driven local optimization for shard allocation
• Lightweight algorithm reduces computation and storage overhead
• Beacon chain handles client-initiated shard migration requests