Communicating memory transactions

Abstract

Many concurrent programming models enable both transactional memory and message passing. For such models, researchers have built increasingly efficient implementations and defined reasonable correctness criteria, while it remains an open problem to obtain the best of both worlds. We present a programming model that is the first to have opaque transactions, safe asynchronous message passing, and an efficient implementation. Our semantics uses tentative message passing and keeps track of dependencies to enable undo of message passing in case a transaction aborts. We can program communication idioms such as barrier and rendezvous that do not deadlock when used in an atomic block. Our experiments show that our model adds little overhead to pure transactions, and that it is significantly more efficient than Transactional Events. We use a novel definition of safe message passing that may be of independent interest.

Chocola

“…Similarly, Transaction Communicators [47] are a special type of object through which transactions can communicate, but again breaking isolation. Third, Communicating Memory Transactions [45] combine transactions with message passing over channels. When a message is sent, a dependency is introduced from the receiver to the sender, similar to our approach.…”

Software Transactional Memory with Interactions

“…Other authors have proposed events-and message passing-based mechanisms; we mention transactional events (TE) [1], which are specialized to the composition of send/receive operations to simplify synchronization in communication protocols, and TIC [21], where a transaction can be split into an isolated and a non-isolated transactions; this may violate local invariants and hence TIC does not satisfy opacity. Finally, communicating memory transactions (CMT) [8] is a model combining memory transactions with the actor model yielding transactors; hence CMT can be seen as the message-oriented counterpart of TC. CMT is opaque and has an efficient implementation; however it is best suited to distributed scenarios, whereas TC and OTM are aimed to multi-threaded programming on shared memory-in fact, transactors can be easily implemented in OTM by means of queues on shared memory.…”

Distinguishing between communicating transactions

“…Transactional constructs without the isolation principle have been proposed as useful building blocks of distributed systems (e.g., [10,11,17,23,3,6]). Communicating transactions is such a construct, equipped with a rich theory providing techniques for proving behavioural equivalence of transactional systems [8,9,16].…”