parallelmachine

A parallel machine is a system composed of two or more processing units that operate concurrently to perform tasks or computations. The term is used in computing to describe hardware architectures that execute multiple processes simultaneously, and in operations research to describe environments where jobs are assigned to several machines working in parallel. Parallel machines can be homogeneous, where units have identical capabilities, or heterogeneous, where speeds and features differ.

In computer architecture, parallel machines range from multicore processors and symmetric multiprocessing systems to distributed clusters and supercomputers. They enable higher throughput and reduced completion time by distributing work across processors. Key concerns include task partitioning, communication overhead, synchronization, and fault tolerance.

In scheduling theory, parallel machine models formalize job assignment problems and are categorized by machine characteristics: identical machines (same speed and capability), uniform machines (different speeds but proportional processing), and unrelated machines (processing time depends arbitrarily on both job and machine). Scheduling objectives include minimizing makespan, total completion time, or tardiness, and many variants are computationally hard, motivating approximation and heuristic methods.

Applications of parallel machines span scientific computing, data centers, manufacturing lines, and real-time systems. Effective use requires consideration of workload balancing, resource contention, latency, and energy efficiency. Ongoing developments address scalability, heterogeneous resources, and scheduling under uncertainty.