Invitation - Talk Prof. João Lourenço, NOVA University Lisbon, Portugal: "Using Pot and LSD to improve ACID transactions" - 08/12/2022 at 16:15 h

On Thursday, 08/12/2022, Prof. João Lourenço from the University of Lisbon, Portugal will be a guest at the Institute of Software Engineering and Programming Languages and will give a talk:

TITLE: Using Pot and LSD to improve ACID transactions (Abstract and Short Bio: see below)

Time: 16:15 h  -  Room: AM S3 - Audimax

Interested parties are cordially invited to attend this talk with the possibility of a discussion afterwards.

State machine replication (SMR) is one of the most popular ways to achieve fault tolerance. In a nutshell, the state machine replication approach maintains multiple replicas that both store a copy of the system’s data and execute operations on that data. When requests to execute operations arrive, an “agree-execute” protocol keeps replicas synchronized: they first agree on an order to execute the incoming operations, and then execute the operations one at a time in the agreed upon order, so that every replica reaches the same final state.  Nowadays, with multicores processors, there is a clear tension in SMR: on the one hand we want to improving performance by taking advantage of the available processor cores to execute multiple operations simultaneously, and on the other hand we need to enforce the replicas to abide to the operation order that they agreed upon, so that the system remains consistent.

In this talk we will address this tension in three steps:  We (1) propose to execute operations as serializable transactions, (2) we propose Pot, a new concurrency control protocol that ensures that the concurrent execution of a set of transactions respects a pre-defined serialization order, and (3) we propose LSD — a modification to the typical API to declare transactions — which allows transactions to execute their logic over an abstract replica state, which results in smaller contention windows and fewer conflicts between transactions, thus improving performance by improving the effectiveness of the speculative executions. The experimental evaluation shows an increase of ≈4× in the system throughput, w.r.t. a traditional (sequential) state-machine-replicated solution.

João Lourenço ( received his doctoral degree in 2004 from the NOVA University Lisbon, Portugal, where he holds a position as Associate Professor in the Computer Science Department. He is a founding member and senior researcher of the NOVA Laboratory for Computer Science and Informatics (NOVA LINCS), and his primary research interests include data management for highly-parallel computing systems, and verification and validation of concurrent programs. He was/is a member of the advisory board and steering committees of several International Conferences and Research Networks, is co-author of more than 70 articles/papers, and received several best paper awards. In his free time he likes to swim, to ride his bicycle in the mountains, and has lots fun being the LaTeX guru for the popular LaTeX thesis template NOVAthesis (  He also writes articles about technical and scientific communication, with or without LaTeX and the NOVAthesis template.