Bounded Concurrent Timestamp Systems Using Vector Clocks

Shared registers are basic objects used as communication mediums in asynchronous concurrent computation. A concurrent timestamp system is a higher typed communication object, and has been shown to be a powerful tool to solve many concurrency control problems. It has turned out to be possible to construct such higher typed objects from primitive lower typed ones. The next step is to find efficient constructions. We propose a very efficient wait-free construction of bounded concurrent timestamp systems from 1-writer multireader registers. This finalizes, corrects, and extends, a preliminary bounded multiwriter construction proposed by the second author in 1986. That work partially initiated the current interest in wait-free concurrent objects, and introduced a notion of discrete vector clocks in distributed algorithms.Comment: LaTeX source, 35 pages; To apper in: J. Assoc. Comp. Mac

Department of Computer Science Activity 1998-2004

This report summarizes much of the research and teaching activity of the Department of Computer Science at Dartmouth College between late 1998 and late 2004. The material for this report was collected as part of the final report for NSF Institutional Infrastructure award EIA-9802068, which funded equipment and technical staff during that six-year period. This equipment and staff supported essentially all of the department\u27s research activity during that period

Optimality of wait-free atomic multiwriter variables

Known implementations of concurrent wait-free atomic shared mul-tiwriter variables use Θ(n) control bits per subvariable. It has been shown that implementations of sequential time-stamp systems require Ω(n) con-trol bits per subvariable. We exhibit a sequential wait-free atomic shared multiwriter variable construction using log n control bits per subvariable. There arises the question of the optimality of concurrent implementations of the same, and of weak time-stamp systems. We also show that our solu-tions are self-stabilizing

Optimality of Wait-Free Atomic Multiwriter Variables

Known implementations of concurrent wait-free atomic shared multiwriter variables use Q(n) control bits per subvariable. It has been shown that implementations of sequential time-stamp systems require W(n) control bits per subvariable. We exhibit a sequential wait-free atomic shared multiwriter variable construction using log n control bits per subvariable. There arises the question of the optimality of concurrent implementations of the same, and of weak time-stamp systems. We also show that our solutions are self-stabilizing. [Information Processing Letters, 43(1992), 107-112] 1980 Mathematics Subject Classification: 68C05, 68C25, 68A05, 68B20. CR Categories: B.3.2, B.4.3, D.4.1, D.4.4. Keywords and Phrases: Shared variable (register), concurrent reading and writing, atomicity, multiwriter variable, simulation. Note: this paper will be published elsewhere. -- -- - 2 - 1. Introduction In [La] it is shown how an atomic variable---one whose accesses appear to be indivisible---shared b..