Developing a Distributed System for Algebraic Geometry -- Non-Determinism and Speculation

Go backward to Functional Parallelism
Go up to Programming Interface
Go forward to Shared Data Objects

Non-Determinism and Speculation

The performance of a parallel program may be improved by processing the results of a set of tasks not in a predetermined order but in the order in which they happen to arrive. Therefore we need a non-deterministic form of task synchronization; this is especially useful in speculative algorithms where the results of some tasks may turn out to be not of interest any more:

dist[select](tlist): blocks the execution of the current task until any task t in the list of task handles tlist has terminated and returns a list r such that r[1] is the result of t and r[2] is the index of t in tlist.
dist[delete](t): announces that the result of task t is not required any more. If this task has not yet started execution, it will be deleted from the system (however, if it has already started, it will continue execution until termination).

Maintained by: Wolfgang Schreiner
Last Modification: April 22, 1999