C# Parallel programming
- 1. by Umesh
- 2. Parallel Programming Most of computers manufacture with multi cores Server application will handle each request in separate threads. Parallel programming basically for Desktop applications. Desktop implementation Partitioning codes into small chunks Execute those chunks in multi threads Collate all the results from the threads, in a thread-safe and perform ant manner. Its awkward to handle with threads particularly partitioning and collating. Parallel programming is designed with set of API’s specifically handle these scenario.
- 3. Parallel Programming Programming to leverage multicores or multiple processors is called parallel programming. This is a subset of the broader concept of multithreading. Parallel programming is the general discipline of doing multiple computations in parallel, using multiple cores, each of which is doing some sub computation of a larger single problem. Where as Multithreading is the approach of using multiple threads of execution to process different operations, e.g. if you have two things to do, use one thread to do one and another thread to do the other. An operating system is able to take handle thread execution in available cores. New .net parallel API’s take maximum advantage of available CPU resources.
- 6. Parallel Programming Task Parallel Library (TPL) PLINQ Data Parallelism Parallel.For Parallel.ForEach Parallel.Invoke Task Parallelism Task
- 7. Task Parallel Library (TPL) TPL provides set of API to implement parallel processing. TPL is to make developers more productive by simplifying the process of adding parallelism and concurrency to applications. The TPL scales the degree of concurrency dynamically to most efficiently use all the processors that are available. the TPL handles the partitioning of the work, the scheduling of threads on the ThreadPool, cancellation support and state management.
- 8. PLINQ (Parallel LINQ) PLINQ offers the richest functionality: it automates all the steps of parallelization—including partitioning the work into tasks, executing those tasks on threads, and collating the results into a single output sequence PLINQ is to speed up the execution of LINQ to Objects queries by executing the query delegates in parallel on multi-core computers. PLINQ queries scale in the degree of concurrency based on the capabilities of the host computer. Syntax- from num in source.AsParallel() where num % 10 == 0 select num;
- 9. Data Parallelism The same operation is performed concurrently on elements in a source collection or array. The source collection is partitioned so that multiple threads can operate on different segments concurrently. Parallel – class available in System.Thread.Tasks namespace For() - Performs the parallel equivalent of a C# for loop ForEach() - Performs the parallel equivalent of a C# foreach loop Invoke () - method provides a convenient way to run any number of arbitrary statements concurrently. That mean, executes an array of Action delegates in parallel, and then waits for them to complete
- 10. TaskParallelism It refers to one or more independent tasks running concurrently. A task represents an asynchronous operation, and in some ways it resembles the creation of a new thread or ThreadPool work item,. Benefits of taks. Tune a task’s scheduling Establish a parent/child relationship when one task is started from another Implement cooperative cancellation Wait on a set of tasks—without a signaling construct Attach “continuation” task(s) Schedule a continuation based on multiple antecedent tasks Propagate exceptions to parents, continuations, and task consumers Dispose the task, it will dispose associated object in the task. The Parallel class and PLINQ are internally built on the task parallelism constructs. Task parallelism is the lowest-level approach to parallelization. The following way to create Task, class available in System.Threading.Tasks namespace Task - For managing a unit for work Task<Tresult> - For managing a unit for work with a return value TaskFactory - For creating tasks TaskFactory<Tresult> - For creating tasks and continuations with the same return type