INTER-ENTRY SELECTION - NONDETERMINISM AND EXPLICIT CONTROL MECHANISMS

Many concurrent programming languages provide selection statements, which allow a task to select one of several entries to service. The choice as to which entry will be selected, if more than one has pending invocations, is generally defined to be non-deterministic. However, such non-deterministic inter-entry selection can result in undesirable program behavior. This paper examines the problems arising from such behavior and the existing approaches to remedy those problems. It indicates the inherent shortcomings of these approaches and purposes a new, more expressive extension of these approaches that remedies these shortcomings. This paper also considers how the different approaches can be implemented.