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Unified Parallel C (UPC) is an extension of theC programming language designed forhigh-performance computing on large-scaleparallel machines, including those with a common globaladdress space (SMP andNUMA) and those withdistributed memory (e.g.clusters). Theprogrammer is presented with a singlepartitioned global address space, where shared variables may be directly read and written by anyprocessor, but each variable is physically associated with a single processor. UPC uses asingle program, multiple data (SPMD) model of computation in which the amount of parallelism is fixed at program startup time, typically with a singlethread of execution per processor.

In order to express parallelism, UPC extendsISO C 99 with the following constructs:

• An explicitly parallel execution model
• A shared address space (shared storage qualifier) with thread-local parts (normal variables)
• Synchronization primitives and a memory consistency model
• Explicit communication primitives, e.g.upc_memput
• Memory management primitives

The UPC language evolved from experiences with three other earlier languages that proposed parallel extensions to ISO C 99: AC,Split-C, and Parallel C preprocessor (PCP). UPC is not asuperset of these three languages, but rather an attempt to distill the best characteristics of each. UPC combines the programmability advantages of the shared memory programming paradigm and the control over data layout and performance of themessage passingprogramming paradigm.

• Cilk
• Coarray Fortran
• Chapel
• X10
• High Performance Fortran
• OpenMP
• Partitioned global address space
• Parallel programming model
• Software transactional memory

• Official website
• UPC at LBNL
• UPC at GWUArchived 2012-07-08 at theWayback Machine
• GNU UPC
• UPC Tutorial (2003)

• Concurrent programming languages
• Parallel computing
• C programming language family

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