Development of scalable parallel programs in ParJava environment

Abstract

This chapter discusses the ParJava integrated environment supporting the development and maintenance of data-parallel Java-programs. When a parallel program is developed it is necessary to assure not only its correctness, but also its efficiency and scalability. For this purpose it is useful to know some dynamic properties of the program (e.g., profiles, traces, slices, etc.). This information may help to modify the program in order to improve its parallel features. ParJava provides a collection of such tools. Symbolic execution allows estimating expected execution time and limits of scalability of Java SPMD-program. SPMD-programs are characterized by sufficiently high level of data exchange among nodes during run time. A linear algebraic system solution program using iterative algorithm may be considered as a simple example of an SPMD-program. The program executes an iterative loop (a parallel loop executed within a sequential loop). There is a great deal of interest in using Java for scientific and engineering computations. The idea of using Java for parallel computations is widely discussed. The most part of SPMD-programs are implemented using the MPI interface (C+MPI, FORTRAN+MPI). There are several implementations of MPI interface for Java. The ParJava environment is on the stage of evolution. The new instrumental tools are being developed (the automatic program parallelizer, the relative debugger of SPMD-programs and other codes), the problem of performance growth of parallel Java programs is under investigation, and the possibilities to apply the Java environment during the preparation of programs for GRID are also studied.