Irregular Parallel Algorithms in JAVA

The nested data-parallel programming model supports the design and implementation of irregular parallel algorithms. This paper describes work in progress to incorporate nested data parallelism into the object model of Java by developing a library of collection classes and adding a forall statement to the language. The collection classes provide parallel implementations of operations on the collections. The forall statement allows operations over the elements of a collection to be expressed in parallel. We distinguish between shape and data components in the collection classes, and use this distinction to simplify algorithm expression and to improve performance. We present initial performance data on two benchmarks with irregular algorithms, EM3d and Convex Hull, and on several microbenchmark programs.