Process Synchronization with Readers and Writers Revisited

The readers-writers problem is one of the very well known problems in concurrency theory. It was first introduced by Courtois et.al. in 1971 [1] and requires the synchronization of processes trying to read and write a shared resource. Several readers are allowed to access the resource simultaneously, but a writer must be given exclusive access to that resource. Courtois et.al. gave semaphore-based solutions to what they called the first and second readers-writers problems. Both of their solutions are prone to starvation. The first allows readers to indefinitely lock out writers and the second allows writers to indefinitely lock out readers. This paper presents and proves correct a third semaphore-based solution, which is starvation-free for both reader and writer processes. To the best of our knowledge, this is the first fair semaphore-based solution that at the same time allows several readers to access the resource simultaneously

Data Management Systems (DMS): Complex data types study. Volume 1: Appendices A-B. Volume 2: Appendices C1-C5. Volume 3: Appendices D1-D3 and E

Two categories were chosen for study: the issue of using a preprocessor on Ada code of Application Programs which would interface with the Run-Time Object Data Base Standard Services (RODB STSV), the intent was to catch and correct any mis-registration errors of the program coder between the user declared Objects, their types, their addresses, and the corresponding RODB definitions; and RODB STSV Performance Issues and Identification of Problems with the planned methods for accessing Primitive Object Attributes, this included the study of an alternate storage scheme to the 'store objects by attribute' scheme in the current design of the RODB. The study resulted in essentially three separate documents, an interpretation of the system requirements, an assessment of the preliminary design, and a detailing of the components of a detailed design

Synchronization of processes

The study of the synchronization of processes is a very interesting field. It-brings together concepts that have originated in the design of operating systems, and of high level programming languages. Also it is becoming clear that the design of algorithms for parallel execution is intimately connected with synchronization problems. Some specialized synchronization problems have arisen in the design of data base systems. Indeed, distributed data bases provide an example of distributed processing that has immense practical significance. To summarize, synchronization of processes is a universal activity whose importance is being felt throughout computer science. The time has therefore come for the synchronization of processes to be studied as a topic in its own right. In this course I am taking such a broad viewpoint, and am trying to integrate some aspects of operating systems, languages, and parallel algorithms. However, this being a first attempt, the integration is not as thorough as I would have wished. Also, in the short time at my disposal, I am not able to discuss several very important topics, such as reliability

Semantics of communicating parallel processes.

Thesis. 1975. Ph.D.--Massachusetts Institute of Technology. Dept. of Electrical Engineering and Computer Science.Bibliography: leaves 187-189.Ph.D

Compositional verification and specification of refinement for reactive systems in a dense time temporal logic

Dissertation zur Erlangung des Doktorgrades der Technischen Fakultat der Christian-Albrechts-Universitat zu Kiel. Originally available in German?This thesis introduces a compostitional dense time temporal logic for the compositions and refinement of reactive systems. A reactive system is specified by a pair consisting of a machine and a condition on the computations of this machine. In order to compose reactive systems, each step in a computation has additionally composition information such as “this is a system step”, or “this is an environment step” or “this is a communication step”. By defining a merge operator that merges two steps into one step compostionality is achieved. Because a dense time temporal logic is used refinement can be expressed easily in this logic. Existing proof rules for refinement are reformulated in our formalism. The notion of relative refinement is introduced to handle refinement of systems that only under certain conditions are considered to be correct refinements. The proof rules for “normal” refinement are extended to handle relative refinement of systems. Relative refinement is used to formalize Dijkstra’s development strategy for the solution of the readers/writers problem and to formalize a development strategy for certain fault tolerant systems. This development strategy is applied to the development of a fault tolerant storage system