Shared memory multiprocessors and sequential programming languages: a case study

The Chrysalis operating system for the BBN Butterfly parallel processor provides a flexible, object-oriented, shared-memory environment for parallel programming. C++ is a safe, sequential, object-oriented programming language. The pairing of these environments is seen potentially as a natural fit. The development of Chrysalis++, and interface between C++ and Chrysalis, indicates that subtle assumptions within each system lead to surprising inconsistencies. Any combination of sequential programming language and shared-memory multiprocessor operating system is likely to be plagued by these inconsistencies because they center around differing assumptions on the nature of the computational environment. The author describes some of the inconsistencies that arose during the development of Chrysalis++ and suggests possible solutions.<>