D 2 STM : Dependable Distributed Software Transactional Memory ∗

Software Transactional Memory (STM) systems have emerged a s a powerful paradigm to develop concurrent applications. At current date, however, t he problem of how to build distributed and replicated STMs to enhance both dependability and performance is still largely unexplored . This paper fills this gap by presenting D STM, a replicated STM that makes use of the computing resources available at multiple nodes of a distributed system . The consistency of the replicated STM is ensured in a transparent manner, even in the presence of fa ilures. In DSTM transactions are autonomously processed on each node, avoiding any replica int er-communication during transaction execution, and without incurring in deadlocks. Strong cons istency is enforced at transaction commit time by a non-blocking distributed certification scheme, wh ich we name BFC (Bloom Filter Certification). BFC exploits a novel Bloom Filter-based encoding m echanism that permits to significantly reduce the overheads of replica coordination at the cost of a user tunable increase in the probability of transaction abort. Through an extensive experimental st udy based on standard STM benchmarks we show that the BFC scheme permits to achieve remarkable per formance gains even for negligible (e.g. 1%) increases of the transaction abort rate.