Java’s insecure parallelism

Abstract: The author examines the synchronization features of Java and finds that they are insecure variants of his earliest ideas in parallel programming published in 1972-73. The claim that Java supports monitors is shown to be false. The author concludes that Java ignores the last twenty-five years of research in parallel programming languages. Zeywords: programming languages; parallel programming; monitors; security; Java; We must expect posterity to view with some asperity the marvels and the wonders we're passing on to it; but it should change its attitude to one of heartfelt gratitude when thinking of the blunders we didn't quite commit. 1. PLATFORM-INDEPENDENT PARALLEL PROGRAMMING Pier Hein (1966) Java has resurrected the well-known idea of platform-independent parallel program-ming. In this paper I examine the synchronization features of Java to discover their origin and determine if they live up to the standards set by the invention of monitors and Concurrent Pascal a quarter of a century ago. In the 1970s my students and I demonstrated that it is possible to write nontriv-ial parallel programs exclusively in a secure language that supports monitors. The milestones of this work were: • The idea of associating explicit queues with monitors [Brinch Hansen 1972]. • A class notation for monitors [Brinch Hansen 1973]. • A monitor language, Concurrent Pascal [Brinch Hansen 1975a]. • A portable compiler that generated platform-independent parallel code [Hart-mann 1975]. • A portable interpreter that ran platform-independent parallel code on a wide variety of computers [Brinch Hansen 1975b]