Inherent limitations on disjoint-access parallel implementations of transactional memory

Hagit Attiya (1) , Eshcar Hillel (2) , Alessia Milani (3)

1 Department of Computer Science
2 Technion - Israel Institute of Technology [Haifa]
3 LaBRI - Laboratoire Bordelais de Recherche en Informatique

Transactional memory (TM) is a promising approach for designing concurrent data structures, and it is essential to develop better understanding of the formal properties that can be achieved by TM implementations. Two fundamental properties of TM implementations are disjoint-access paral- lelism, which is critical for their scalability, and the invisi- bility of read operations, which reduces memory contention. This paper proves an inherent tradeoff for implementa- tions of transactional memories: they cannot be both disjoint- access parallel and have read-only transactions that are in- visible and always terminate successfully. In fact, a lower bound of Ω(t) is proved on the number of writes needed in order to implement a read-only transaction of t items, which successfully terminates in a disjoint-access parallel TM im- plementation. The results assume strict serializability and thus hold under the assumption of opacity. It is shown how to extend the results to hold also for weaker consistency conditions, serializability and snapshot isolation.

Domaines: Calcul parallèle, distribué et partagé [cs.DC]

Hagit Attiya, Eshcar Hillel, Alessia Milani. Inherent limitations on disjoint-access parallel implementations of transactional memory. SPAA, 2009, Unknown, pp.69-78, ⟨10.1145/1583991.1584015⟩. ⟨hal-00992693⟩