Software Transactional Memory with Interactions

TL;DR

This paper introduces Open Transactional Memory (OTM), a novel STM model that enables safe, data-driven interactions between transactions by relaxing isolation while maintaining atomicity, thus enhancing concurrent programming flexibility.

Contribution

The paper presents OTM, a new STM abstraction allowing transactions to interact dynamically through shared data without prior participant specification, addressing limitations of traditional isolated STM models.

Findings

OTM supports safe, data-driven interactions between transactions.

OTM maintains atomicity despite relaxed isolation.

Enables more flexible concurrent programming models.

Abstract

Software Transactional memory (STM) is an emerging abstraction for concurrent programming alternative to lock-based synchronizations. Most STM models admit only isolated transactions, which are not adequate in multithreaded programming where transactions need to interact via shared data before committing. To overcome this limitation, in this paper we present Open Transactional Memory (OTM), a programming abstraction supporting safe, data-driven interactions between composable memory transactions. This is achieved by relaxing isolation between transactions, still ensuring atomicity. This model allows for loosely-coupled interactions since transaction merging is driven only by accesses to shared data, with no need to specify participants beforehand.