Hoãn lại các cuộc gọi đồng bộ cho phép khách hàng để thăm dò ý kiến trên một phản ứng chậm từ máy chủ. Sự kiện dịch vụ cho phép người tiêu dùng dụng các sự kiện yêu cầu hoặc được thông báo về | ISSUES IN HPC SOFTWARE DEVELOPMENT 191 Parallel Algorithm Development The utilization of HPC systems depends on the availability of efficient parallel algorithms. Parallel extensions or implementations of existing sequential algorithms are not able to exploit the parallelism inherent in the problem because this information usually is lost or hidden during development of the sequential version. Consequently high-performance software warrants the development of new algorithms which are specifically designed to exploit parallelism at every level. Issues related to parallel algorithm development include Algorithm classification the ability to classify algorithms on the basis of their computational and communication characteristics so that algorithms can be matched with target HPC architectures during software development Algorithm evaluation the ability to evaluate an algorithm to obtain a realistic estimate of its complexity or potential performance enabling the developer to evaluate different algorithms for a problem and to make an appropriate selection Algorithm mapping the assignment of the parallel algorithm to an appropriate HPC system based on algorithm classification and system specifications Program Implementation and Runtime Program implementation issues address system specific decisions made during program development such as synchronization strategies data decomposition vectorization strategies pipelining strategies and load balancing. These issues define the requirements of a parallel programming environment which include parallel language support syntax-directed editors intelligent compilers and cross-compilers parallel debuggers configuration management tools and performance evaluators. Runtime issues include providing efficient parallel runtime libraries dynamic scheduling and load-balancing support as well as support for nonintrusive monitoring and profiling of application execution. Visualization and Animation Since HPC systems can .
