1989 Reports

System Support for "Multiple Worlds"

Smith, Jonathan M.; Maguire, Gerald Q.

Concurrently computing alternative solutions to a problem can be used as a method to improve response time. In order to maintain internal consistency despite differences caused by alternative solution methods, "Multiple Worlds" are created. This paper examines the operating system requirements posed by such a method. Problems include (1) side-effects and (2) combinatorial explosion in the amount of state which must be preserved. We solve these by process management and an application of "copy-on-write" virtual memory management. Side effects resulting from interprocess communication are handled by a specialized message layer which interacts with process management.