In this post, we’ll investigate some ways that Parallel Extensions can be used to introduce parallelism and asynchrony to I/O scenarios. Here’s a simple scenario. I want to retrieve data from a number of web resources. static string[] Resources = new string[] { "http://www.microsoft.com", "http://www.msdn.com", ...
One of the ways in which the Task Parallel Library achieves good performance is through “work-stealing”. Work-stealing is supported in the .NET 4 ThreadPool for access through the Task Parallel Library and its default scheduler. This manifests as every thread in the ThreadPool having its own queue for work; when that thread ...
More and more, developers are realizing the significant scalability advantages that asynchronous programming can provide, especially as it relates to I/O. Consider an application that needs to copy data from one stream to another stream, such as is being done in the following synchronous implementation: static void CopyStreamToStream(Stream input...
In a previous post, it was demonstrated how for loops with very small loop bodies could be parallelized by creating an iterator over ranges, and then using Parallel.ForEach over those ranges. A similar technique can be used to write parallel loops over iteration spaces of non-integers. For example, let’s say I wanted to paralleliz...
One of the great features that crosses all of Parallel Extensions types is a consistent approach to cancellation (see https://blogs.msdn.com/pfxteam/archive/2009/05/22/9635790.aspx). In this post we explore some of the ways cancellation is used in Parallel Extensions and explain the guidance we developed. The new cancellation system is a cooperativ...
As has been discussed previously, one of the new features in the Task Parallel Library is TaskCompletionSource<TResult>, which enables the creation of a Task<TResult> that represents any other asynchronous operation. There are a wide variety of sources in the .NET Framework for asynchronous work. One comes from components th...
The Asynchronous Programming Model (APM) in the .NET Framework has been around since .NET 1.0 and is the most common pattern for asynchrony in the Framework. Even if you’re not familiar with the name, you’re likely familiar with the core of the pattern. For a given synchronous operation Xyz, the asynchronous version manifest...
The Parallel class represents a significant advancement in parallelizing managed loops. For many common scenarios, it just works, resulting in terrific speedups. However, while ideally Parallel.For could be all things to all people, such things rarely work out, and we’ve had to prioritize certain scenarios over others.One area Par...
The core entity in the Task Parallel Library around which everything else revolves is System.Threading.Tasks.Task. The most common way of creating a Task will be through the StartNew method on the TaskFactory class, a default instance of which is exposed through a static property on Task, e.g. var t = Task.Factory.StartNew(() => { &n...
The Task Parallel Library is centered around the Task class and its derived Task<TResult>. The main purpose of these types is to represent the execution of an asynchronous workload and to provide an object with a means to operate on that workload, whether it be to wait for it, to continue from it, or the like. The primary type of asynchronous...
