Testing Speculative Work in a Lazy/Eager Parallel Functional Language

Abstract

Eden is a parallel extension of the functional language Haskell. Eden inherits from Haskell its laziness, which allows it to avoid unnecessary computations. However, in order to enable the parallel execution of processes in Eden, this feature must be disabled when new processes are instantiated. Hence, any newly created process can be speculative, as it is not known whether the computations it performs will actually be required for the overall computation. Therefore, the performance of a program may be affected by the unneeded speculation. In this paper we present a framework to compare the speculated computations of an Eden program with the computations it actually requires. Thus, the programmer is provided with a profiling tool allowing him to produce better programs where speculative work fits better the actual necessities.