João Rafael Pinto Soares

An Architecture to Offer Transactional Strong Consistency for FaaS Applications

Tese submetida para provas de mestrado em Engenharia Informática e de Computadores Instituto Superior Técnico, Universidade de Lisboa.


Function-as-a-Service (FaaS) is a relatively recent paradigm supported by many cloud providers that supports the execution of applications without prior allocation of servers. Applications are written as a composition of stateless functions, organized in a graph. Different functions may execute in different servers, that are provisioned automatically by the cloud provider. Functions may read and write from/to stable storage using a storage service of their choice. For cost/efficiency reasons, most FaaS applications use storage services that cannot provide strong consistency to functions executing in different servers. In this thesis we study efficient ways of extending a weakly consistent data store with additional services that can offer transactional support and strong consistency (namely, snapshot isolation) to FaaS applications. Some previous works that aim at achieving the same goals force all storage read- /write requests to be forwarded to one or more consistency servers, that are responsible for ensuring that a consistent version of the data is returned to the functions. In this work we propose and evaluate a different strategy, where functions read optimistically from storage and use the consistency servers to obtain metadata that is used to check if the version returned by the storage system is consistent. This strategy decreases the load on the consistency server, improving the scalability of the system. Our experimental evaluation shows that our solution offers 1.4× higher throughput then alternative protocols, while using only 5% of their resources.


An Architecture to Offer Transactional Strong Consistency for FaaS Applications
João Rafael Pinto Soares
MSc Thesis. Instituto Superior Técnico, Universidade de Lisboa.
November 2021.
Available BibTeX, MSC Thesis, and extended abstract, and mid-term report.
Uma Arquitectura para Oferecer Garantias de Coerência forte a Aplicações FaaS.
R. Soares and L. Rodrigues
Actas do décimo segundo Simpósio de Informática (Inforum), Lisboa, Portugal, Sep. 2021.
Available BibTeX, extended report (pdf).
FaaSTCC: Efficient Transactional Causal Consistency for Serverless Computing.
T. Lykhenko, R. Soares and L. Rodrigues.
Proceedings of the 22nd ACM/IFIP International Middleware Conference, Virtual Event, Canada, December 2021.

Luís Rodrigues