The Howdy Glossary

Unified Parallel C (UPC) is a high-level parallel programming language developed to facilitate inter-process communication in distributed-memory environments, optimized for supercomputers and high-performance computing clusters. Extending the traditional C programming language, it employs the Single Program Multiple Data (SPMD) model to express parallelism efficiently. This enables developers to write code that can run on multiple processors while incorporating system-specific optimizations and maintaining portability across various parallel architectures.

Developed by researchers at the University of Illinois at Urbana-Champaign's Center for Reliable and High-Performance Computing (CRPC) and the Parallel Programming Laboratory (PPL), UPC addresses challenges specific to supercomputing and high-performance computing clusters. The language's constructs enable communication between processes running on different processors, providing flexibility for varied control paths based on process IDs within a single program. Its design focuses on both user-friendliness for experienced C programmers and efficiency in expressing fine-grained data locality while supporting system-specific optimizations.

UPC competes with other high-level parallel programming languages like MPI, OpenMP, and Chapel but distinguishes itself by extending C with specific features for distributed-memory environments. Unlike MPI’s low-level control or OpenMP’s focus on shared memory systems, UPC offers ease of use in inter-process communication while being suitable for distributed-memory settings. It allows seamless integration with existing C codebases and libraries without sacrificing performance or usability. This makes it ideal for experienced C programmers aiming to leverage parallel computing capabilities efficiently across diverse parallel architectures without compromising portability or ease of development.