RENOIR: Accelerating Blockchain Validation using State Caching

ABSTRACTA Blockchain system such as Ethereum is a peer to peer network where each node works in three phases: creation, mining, and validation phases. In the creation phase, it executes a subset of locally cached transactions to form a new block. In the mining phase, the node solves a cryptographic puzzle (Proof of Work-PoW) on the block it forms. On receiving a block from another peer, it starts the validation phase, where it executes the transactions in the received block in order to ensure all transactions are valid. This execution also updates the blockchain state, which must be completed before creating the next block. A long block validation time lowers the system's overall throughput and brings the well known Verifier's dilemma into play. Additionally, this leads to wasted mining power utilization (MPU). Through extensive measurement of 2000 nodes from the production Ethereum network we find that during block validation, nodes redundantly execute more than 80% of the transactions in greater than 75% of the blocks they receive - this points to significant potential to save time and computation during block validation. Motivated by this, we present RENOIR, a novel mechanism that caches state from transaction execution during the block creation phase and reuses it to enable nodes to skip (re)executing these transactions during block validation. Our detailed evaluation of RENOIR on a 50 node testbed mimicking the top 50 Ethereum miners illustrates that when gas limit is increased to 20 times the default value, to accommodate computationally intensive transactions, RENOIR reduces validation time by 90% compared to Ethereum. In addition, throughput of Ethereum reduces from 35326 tx/hour to 24716 tx/hour and MPU from 96% to 67% but these barely change for RENOIR. Furthermore, we deploy a node running RENOIR on the production Ethereum network. Our measurement illustrates that RENOIR reduces the block validation time by as much as 50%.