Parallel programming environments provide a way for programmers to reap the benefits of parallelism, while reducing the effort required to create parallel applications. The CO2P3S parallel programming system is one such tool that uses a pattern-based approach to express concurrency. Using the Cowichan Problems, we demonstrate that CO2P3S contains a rich set of parallel patterns for implementing a wide variety of applications running on shared-memory or distributed-memory hardware. An example of these parallel patterns, the Search-Tree pattern, is described and it is shown how the pattern was used to solve the Fifteen Puzzle problem. Code metrics and performance results are presented for the Cowichan applications to show the usability of the CO2P3S system and its ability to reduce programming effort, while producing programs with reasonable performance.

Task-based libraries such as Intel’s Threading Building Blocks (TBB) provide higher levels of abstraction than threads for parallel programming. Work remains, however, to determine how straightforward it is to use these libraries to express various patterns of parallelism. This case study focuses on a particular pattern: pipeline parallelism. We attempted to transform three representative pipeline applications — content-based image retrieval, compression and video encoding — to use the pipeline constructs in TBB. We successfully converted two of the three applications. In the successful cases we discuss our transformation process and contrast the expressivity and performance of our implementations to existing Pthreads versions; in the unsuccessful case, we detail what the challenges were and propose possible solutions. Categories and Subject Descriptors D.2.11 [Software Architectures]: Patterns; D.3.3 [Language Constructs and