.NET Parallel Programming

All about Async/Await, System.Threading.Tasks, System.Collections.Concurrent, System.Linq, and more…

Building Async Coordination Primitives, Part 1: AsyncManualResetEvent

February 11, 2012 Feb 11, 2012 02/11/12

Stephen Toub - MSFT

The Task-based Async Pattern (TAP) isn’t just about asynchronous operations that you initiate and then asynchronously wait for to complete. More generally, tasks can be used to represent all sorts of happenings, enabling you to await for any matter of condition to occur. We can even use Tasks to build simple coordination ...

Potential pitfalls to avoid when passing around async lambdas

February 8, 2012 Feb 8, 2012 02/8/12

Stephen Toub - MSFT

One of the really useful capabilities of the new async methods feature in C# and Visual Basic is the ability to write async lambdas and anonymous methods (from here on in this post, I’ll refer to both of these as async lambdas, since the discussion applies equally to both). This allows you to easily get a delegate to represent an ...

When “ExecuteSynchronously” doesn’t execute synchronously

February 7, 2012 Feb 7, 2012 02/7/12

Stephen Toub - MSFT

When creating a task continuation with ContinueWith, developers have the opportunity to provide a TaskContinuationOptions enum value, which could include the TaskContinuationOptions.ExecuteSynchronously flag. ExecuteSynchronously is a request for an optimization to run the continuation task on the same thread that completed the ...

FromAsync(asyncResult, …) vs FromAsync(beginMethod, …)

February 6, 2012 Feb 6, 2012 02/6/12

Stephen Toub - MSFT

The Task Parallel Library (TPL) provides a set of “FromAsync” helper methods that create a Task or a Task<TResult> to represent an invocation of an APM method pair, i.e. BeginXx / EndXx. There are, however, two different flavors among these overloads: ones that accept an IAsyncResult “asyncResult” as the ...

Await, SynchronizationContext, and Console Apps: Part 3

February 2, 2012 Feb 2, 2012 02/2/12

Stephen Toub - MSFT

In Part 1 and Part 2 of this short series, I demonstrated how you can build a SynchronizationContext and use it run an async method such that all of the continuations in that method will run on serialized on the current thread. This can be helpful when executing async methods in a console app, or in a unit test framework that doesn&rsquo...

Advanced APM Consumption in Async Methods

January 23, 2012 Jan 23, 2012 01/23/12

Stephen Toub - MSFT

I’ve previously blogged about how to expose existing Asynchronous Programming Model (APM) implementations as Task-based methods. This can be done manually using a TaskCompletionSource<TResult>, or it can be done using the built-in wrapper provided in TPL via the Task.Factory.FromAsync method. By creating a Task-based ...

Await, SynchronizationContext, and Console Apps: Part 2

January 21, 2012 Jan 21, 2012 01/21/12

Stephen Toub - MSFT

Yesterday, I blogged about how you can implement a custom SynchronizationContext in order to pump the continuations used by async methods so that they may be processed on a single, dedicated thread. I also highlighted that this is basically what UI frameworks like Windows Forms and Windows Presentation Foundation do with their message ...

Implementing a SynchronizationContext.SendAsync method

January 20, 2012 Jan 20, 2012 01/20/12

Stephen Toub - MSFT

I recently saw two unrelated questions, the answers to which combine to form a potentially useful code snippet.The first question was about SynchronizationContext. SynchronizationContext provides a Post method, which asynchronously schedules the supplied delegate and object state to be executed according to the SynchronizationContext&...

Await, SynchronizationContext, and Console Apps

January 20, 2012 Jan 20, 2012 01/20/12

Stephen Toub - MSFT

When I discuss the new async language features of C# and Visual Basic, one of the attributes I ascribe to the await keyword is that it “tries to bring you back to where you were.” For example, if you use await on the UI thread of your WPF application, the code that comes after the await completes should run back on that same UI ...

Awaiting Socket Operations

December 15, 2011 Dec 15, 2011 12/15/11

Stephen Toub - MSFT

The System.Net.Sockets.Socket class in .NET exposes multiple sets of asynchronous methods that perform the same basic operations but that are exposed with different patterns.The first set follows the APM pattern, where for a synchronous method like Receive, the BeginReceive and EndReceive methods are exposed. If you want to be able to &...

.NET Parallel Programming

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