Explicit parallel programming

Abstract

While many parallel programming languages exist, they rarely address programming languages from the issue of communication (implying expressability, and readability). A new language called Explicit Parallel Programming (EPP), attempts to provide this quality by separating the responsibility for the execution of run time actions from the responsibility for deciding the order in which they occur. The ordering of a parallel algorithm is specified in the new EPP language; run time actions are written in FORTRAN and embedded in the EPP code, from which they are later extracted and given to a FORTRAN compiler for compilation.

The separation of order and run time actions is taken to its logical extreme in an attempt to evaluate its benefits and costs in the parallel environment. As part of the evaluation, a compiler and executive were implemented on a Sequent Symmetry 881 shared memory multiprocessor computer. The design decisions and difficulties in implementation are discussed at some length, since certain problems are unique to this approach. In the final evaluation, the EPP project asserts that structured, parallel programming languages require a significant amount of interaction with an over-seeing task in order to provide some basic, desirable functions. It also asserts that the description of run time actions (e.g., expression syntax) need not change from the uniprocessor environment to the multiprocessor environment.