Abstract

Abstract:

Performance and scalability are major concerns for blockchains: permissionless systems are typically limited by slow proof of X consensus algorithms and sequential post-order transaction execution on every node of the network. By introducing a small amount of trust in their participants, permissioned blockchain systems such as Hyperledger Fabric can benefit from more efficient consensus algorithms and make use of parallel pre-order execution on a subset of network nodes. However, this higher performance is only achievable for contention-free transaction workloads. If many transactions compete for a small set of hot keys in the world state, the effective throughput drops drastically. We therefore propose XOX : a novel two-pronged transaction execution approach that both minimizes invalid transactions in the Fabric blockchain and maximizes concurrent execution. Our approach additionally prevents unintentional denial of service attacks by clients re-submitting conflicting transactions. Even under fully contentious workloads, XOX can handle more than 3000 transactions per second, all of which would be discarded by regular Fabric.

Bio:

Christian Gorenflo is a fifth year PhD student at the university of Waterloo, co-supervised by Prof. Lukasz Golab and Prof. Srinivasan Keshav. He received his Diplom (Physics) degree at the Karlsruhe Institute of Technology in 2012. Afterwards he worked as a consultant at Objektkultur Software GmbH before starting a PhD program (Computer Science) at the University of Waterloo in the Information Systems and Science for Energy (ISS4E) research group in 2015. Since 2017 he is part of the Sirius blockchain research group and his research interests focus on performance optimizations for distributed ledger systems. He currently holds the David R. Cheriton Graduate Scholarship.