Reimer Behrends

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Transactional memory is being advanced as an alternative to traditional lock-based synchronization for concurrent programming. Transactional memory simplifies the programming model and maximizes concurrency. At the same time, transactions can suffer from interference that causes them to often abort, from heavy overheads for memory accesses, and from(More)
We present the TIC (Transactions with Isolation and Cooperation) model for concurrent programming. TIC adds to standard transactional memory the ability for a transaction to observe the effects of other threads at selected points. This allows transactions to cooperate, as well as to invoke nonrepeatable or irreversible operations, such as I/O. Cooperating(More)
We present the universe model, a new approach to concurrency management that isolates concurrency concerns and represents them in the modular interface of a component. This approach improves program comprehension, module composition, and reliability for concurrent systems. The model is founded on designer-specified invariant properties, which declare a(More)
The safe and reliable use of concurrency in multi-threaded systems has emerged as a fundamental engineering concern. We recently developed a model of synchronization contracts to address this concern in programs written in object-oriented languages. Programs written using our model comprise modules that declare access requirements in module interfaces in(More)
Standard concurrency control mechanisms offer a trade-off: Transactional memory approaches maximize concurrency, but suffer high overheads and cost for retrying in the case of actual contention. Locking offers lower overheads, but typically reduces concurrency due to the difficulty of associating locks with the exact data that need to be accessed. Moreover,(More)
We previously developed a component-oriented model that combines ideas from self-organizing architectures and from design by contract to address the complexity of design in multi-threaded systems. Components in our model are cohesive collections of objects that publish contracts declaring the conditions under which they access other components. These(More)
It is widely held that programming language extensions that support separation of concerns and that are also inte-grative benefit development, maintenance and reuse of software designs and code. Such is the intent of our Synchronization Units Model (Szumo), which unifies new features for expressing synchronization in a multi-threaded program with existing(More)
We report on the project of parallelising GAP, a system for computational algebra. Our design aims to make concurrency facilities available for GAP users, while preserving as much of the existing code base (about one million lines of code) with as few changes as possible and without requiring users---a large percentage of whom are domain experts in their(More)