Keserentakan
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Dalam sains komputer, keserentakan (concurrency) adalah berkaitan dengan perkongsian sumber asas diantara proses komputasi yang melaksanakan 'overlapped' dalam masa (termasuk larian secara serentak). Ini biasanya melibatkan pencarian teknik yang bersesuaian untuk mengkoordinasikan perlaksanaan, perubahan data, menempatkan memori dan menjadualkan masa pemprosesan dalam cara yang tertentu untuk meminimakan masa tindakbalas dan memaksimakan throughput. Sistem Keserentakan seperti sistem pengoperasian direkabentuk untuk beroperasi Concurrent systems such as operating systems are designed to operate indefinitely and not terminate unexpectedly. However current operating systems in broad use do not fulfill this design goal in practical operation.
Because of the use of shared resources, concurrent systems in general require the use of arbiters in their implementation which gives rise to unbounded nondeterminism.
Levels of coordination can be ranked by coupling -- from tightest to loosest. Generally, the tighter the coupling between concurrent computations and the more use of a shared resource, the more contention there can be for that resource.
Concurrent programming encompasses the programming languages and algorithms used to implement such techniques. It is considered to be more general than parallel programming, because it involves shared resources that can change, whereas parallelism only entails multiple executions at the same time. Its base goals include correctness, performance and robustness.
There are several models of concurrency:
- The Parallel Random Access Machine
- The Actor model
- Petri nets
- Process calculi
The above models can be use in the design, implementation, proof, testing and simulation of concurrent systems. [edit]
[Sunting] Lihat juga
- Concurrency control
- Threads
- Processes
- Nodes in a cluster
- Nodes in a distributed system
- Nodes in a client-server network
- Ptolemy Project
- OpenMP