Concurrent Models for Object Execution

In previous work we developed a framework of computational models for the concurrent execution of functions on different levels of abstraction. It shows that the traditional sequential execution of function is just a possible implementation of an abstract computational model that allows for the concurrent execution of function. We use this framework as base for the development of abstract computational models that allow for the concurrent execution of objects

An abstract machine for restricted and-parallel execution of logic programs

Although the sequential execution speed of logic programs has been greatly improved by the concepts introduced in the Warren Abstract Machine (WAM), parallel execution represents the only way to increase this speed beyond the natural limits of sequential systems. However, most proposed parallel logic programming execution models lack the performance optimizations and storage efficiency of sequential systems. This paper presents a parallel abstract machine which is an extension of the WAM and is thus capable of supporting ANDParallelism without giving up the optimizations present in sequential implementations. A suitable instruction set, which can be used as a target by a variety of logic programming languages, is also included. Special instructions are provided to support a generalized version of "Restricted AND-Parallelism" (RAP), a technique which reduces the overhead traditionally associated with the run-time management of variable binding conflicts to a series of simple run-time checks, which select one out of a series of compiled execution graphs

ABSTRACT EXECUTION OF PROGRAMS

Compilation time analysis of programs is usually incomplete. One of the basic methods for static determination of the program's dynamic properties is symbolic execution. Symbolic execution still fails to satisfy practical requirements, mainly because of the high execution time and memory requirement, theorem proving and program termination problems. In this paper new methods are presented which can make symbolic execution applicable in everyday work, e.g. in programming microprocessor equipment

Parallel Evaluation of Multi-join Queries

A number of execution strategies for parallel evaluation of multi-join queries have been proposed in the literature. In this paper we give a comparative performance evaluation of four execution strategies by implementing all of them on the same parallel database system, PRISMA/DB. Experiments have been done up to 80 processors. These strategies, coming from the literature, are named: Sequential Parallel, Synchronous Execution, Segmented Right-Deep, and Full Parallel. Based on the experiments clear guidelines are given when to use which strategy. This is an extended abstract; the full paper appeared in Proc. ACM SIGMOD'94, Minneapolis, Minnesota, May 24–27, 199

Microgrid - The microthreaded many-core architecture

Traditional processors use the von Neumann execution model, some other processors in the past have used the dataflow execution model. A combination of von Neuman model and dataflow model is also tried in the past and the resultant model is referred as hybrid dataflow execution model. We describe a hybrid dataflow model known as the microthreading. It provides constructs for creation, synchronization and communication between threads in an intermediate language. The microthreading model is an abstract programming and machine model for many-core architecture. A particular instance of this model is named as the microthreaded architecture or the Microgrid. This architecture implements all the concurrency constructs of the microthreading model in the hardware with the management of these constructs in the hardware.Comment: 30 pages, 16 figure

Model-driven design of distributed applications

The design process is structured into a preparation and an execution phase. In the preparation phase, designers identify (and, when necessary, define) the required levels of models, their abstract platforms and the modelling language(s) to be used. In addition, a designer may also identify or define transformations between related levels of models. The results of the preparation phase are used in the execution phase, which entails the creation of models of an application using specific modelling languages and abstract platforms.\ud The main aspects of the approach are illustrated with a case study involving the design of context-aware mobile services. We define three levels of models: a platform-independent service specification level, a platformindependent service design level and a platform-specific service design level. Particular attention is given to the representation and transformation of behavioural aspects of service designs