GARET: improving throughput using gas consumption-aware relocation in Ethereum sharding environments

Abstract

Advances in blockchain technology have made a significant impact on a wide range of research areas due to the features such as transparency, decentralization and traceability. With the explosive growth of blockchain transactions, there has been a growing interest in improving the scalability of blockchain network. Sharding is one of the methods to solve this scalability problem by partitioning the network into several shards so that each shard can process the transactions in parallel. Ethereum places each transaction statically on a shard based on its account address without considering the complexity of the transaction or the load generated by the transaction. This causes the transaction utilization on each shard to be uneven, which makes the transaction throughput of the network decrease. This paper formulates this problem as a multi-dimensional knapsack problem (MKP) and proposes a heuristic algorithm called GARET. The GARET dynamically relocates the transaction load of each shard based on gas consumption to maximize the transaction throughput. Ethereum gas is a unit that represents the amount of computational effort needed to execute operations in a transaction. Benchmarking results show that GARET outperforms existing techniques by up to 12% in transaction throughput and decreases the makespan of transaction latency by about 74% under various conditions. It is also shown that the relocation overhead is minimal and does not affect the overall performance.