Strong Session Serializability for Serverless Computing

Existing works explore various consistency levels to address transactional consistency gaps in serverless platforms but have not explored achieving strong session serializability (3SER) for serverless. For applications with 3SER requirements, stronger transactional consistency is unnecessary and can compromise performance. However, the stateless nature of serverless architectures and their fault-tolerance mechanisms pose challenges in designing a 3SER transaction protocol. We propose TFaaS, the first transactional serverless platform that provides a 3SER guarantee for serverless workflows. TFaaS employs caching to manage session states, transaction execution states, and workflow logs. It selectively persists the necessary states based on time fence techniques to ensure consistency and fault-tolerance requirements are met. Our evaluation demonstrates that TFaaS can effectively reduce latency by up to 6.5× and improve throughput by up to 8×.