Inter-entry selection control mechanisms: Implementation and evaluation

Inter-process communication is achieved in many concurrent programming languages through message entries. Many of these languages contain inter-entry selection constructs allowing a process to selectively choose one of a group of message entries to service. Generally, this selection process is handled non-deterministically. To enable a degree of control over this selection, limited inter-entry selection control mechanisms are available in several of these languages. This paper reviews the need for more expressive inter-entry selection control mechanisms and details the design and implementation of two such control mechanisms—static and dynamic preferences. These implementations of static and dynamic preferences, SRps and SRpd respectively, are extensions of the SR concurrent programming language. In both implementations, the use of preferences is optional, and thus, the overhead associated with their use is incurred only when their use is necessary. Finally, this paper describes the performance of these implementations on several classical synchronization problems. For tests run in a shared memory environment the results show that there is substantial cost associated with the preference implementations. However, the results of the distributed environment tests illustrate that the incremental cost of adding preferences is small and often not discernable when the overhead costs associated with communications across a network are considered.