Integrating synchronous and asynchronous paradigms: the Fork95 parallel programming language

The SB-PRAM is a lock-step-synchronous, massively parallel multiprocessor currently being built at Saarbrucken University, with up to 4096 RISC-style processing elements and with a (from the programmer's view) physically shared memory of up to SGByte with uniform memory access time. Fork95 is a redesign of the PRAM language FORK, based on ANSI C, with additional constructs to create parallel processes, hierarchically dividing processor groups into subgroups, managing shared and private address subspaces. Fork95 makes the assembly-level synchronicity of the underlying hardware available to the programmer at the language level. Nevertheless, it provides comfortable facilities for locally asynchronous computation where desired by the programmer. We show that Fork95 offers full expressibility for the implementation of practically relevant parallel algorithms. We do this by examining all known parallel programming paradigms used for the parallel solution of real-world problems, such as strictly synchronous execution, asynchronous processes, pipelining and systolic algorithms, parallel divide and conquer, parallel prefix computation, data parallelism, etc., and show how these parallel programming paradigms are supported by the Fork95 language and run time system.