EOVPR:Blockchain Architecture Supporting Transaction Reordering And Parallel Validation

The emergence of Bitcoin has drawn people’s attention to its underlying blockchain technology.Currently,applications based on blockchain technology contain many industries such as anti-counterfeiting traceability,digital copyright,public service and healthcare.From the view of transaction processing,permissionless blockchain faces problems such as low efficiency of mining algorithm and slow transaction throughput caused by sequential execution of transactions by each node,while permissioned blockchain entrusts some execution nodes with a small amount of trust and uses efficient consensus algorithm to improve the transaction processing ability of blockchain.Hyperledger Fabric is one of the representatives of permissioned blockchain.The system learns from the idea of optimistic concurrency control to realize the parallel execution of transactions,which improves the transaction throughput of blockchain to a certain extent.However,this efficiency only applies when there is less data competition,and transaction throughput can be significantly reduced if a large number of transactions access the same data and are not checked for validation until the validation phase.Meanwhile,Hyperledger Fabric fails to take full advantage of the mutual trust of nodes in the same organization in the permissioned blockchain.During the validation phase,nodes in the organization validate the same transaction,resulting in redundancy,which limits the scalability of the blockchain network.In addition,the time cost in the validation phase of Hyperledger Fabric obviously limits the end-to-end transaction throughput.As endorsement policy validation in the validation phase involves many digital signature verification,which requires a large amount of computing resources,Hyperledger Fabric occupies a large proportion of the entire validation phase in endorsement policy validation.In view of the above shortcomings,on the basis of the Hyperledger Fabric EOV architecture,a blockchain transaction processing architecture is proposed,i.e.,ExecutionOrder&Validate-parallel-re-execute(EOVPR)which can be carried out simultaneously in the order phase and the validation phase.In this architecture,the work of subsequent endorsement policy validation is assigned to auxiliary nodes with high computing power in advance in the order phase.When order nodes reach a consensus on the transaction order,auxiliary nodes validate the endorsement policies of the transactions.The consensus process of order nodes does not affect the validation work of auxiliary nodes,which greatly reduces the time cost of the subsequent validation phase.In order to ensure the performance of blockchain and abort invalid transactions as soon as possible under high data competition,a transaction reordering strategy is proposed.Reordering transactions received by nodes during execution phase reduces the number of invalid transactions.In the order phase,the transaction conflict analysis component and graph generation component are designed to obtain the conflict relationship between transactions,and the dependency graph is generated based on the reordering algorithm and invalid transactions are aborted.The dependency graph also ensures the correctness of the data in subsequent validation phase.For the invalid transactions detected in the validation phase,they are reexecuted to avoid allowing the invalid transactions to enter a new round of transaction execution process,which improves the transaction throughput of blockchain.In order to speed up the validation efficiency of nodes on transactions,the mutual trust between nodes in the same organization in the permissioned blockchain is utilized to enable each node in the organization to validate different transactions in parallel and synchronize the validation results,thus reducing the delay of validation phase.Meanwhile,the addition of new nodes to the blockchain network can further improve the speed of transaction validation and improve the scalability of blockchain.The experimental results show that the EOVPR architecture,which is proposed to solve the problems in the EOV architecture of Hyperledger Fabric,greatly improves the blockchain performance and transaction throughput,while reducing the system latency.