On Open Nesting in Distributed Transactional Memory

Abstract

Distributed Transactional Memory (DTM) is a recent but promising model for programming distributed systems. It aims to present programmers with a simple to use distributed concurrency control abstraction (transactions), while maintaining performance and scalability similar to distributed fine-grained locks. Any complications usually associated with such locks (e.g., distributed deadlocks) are avoided. Building upon the previously proposed Transactional Forwarding Algorithm (TFA), we add support for open nested transactions. We discuss the mechanisms and performance implications of such nesting, and identify the cases where using open nesting is warranted and the relevant parameters for such a decision. To the best of our knowledge, our work contributes the first ever implementation of a DTM system with support for open nested transactions.

Thrifty-malloc

“…Here, having dedicated transactions for the fallback routine, as discussed in Section 3.3.1, would result in nested transactions. Since nested transactions are not supported by certain transactional memory systems (and semantics vary for those that do [25]), we chose to avoid them.…”

Bumper: Sheltering distributed transactions from conflicts

“…Open nesting has also been used to reduce conflicts in Distributed Transactional Memories [25]: it requires the programmer (a) YCSB (with up to 160 nodes).…”