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 first pa...
I was recently asked by a developer about getting some additional information out of ConcurrentDictionary<TKey,TValue>’s GetOrAdd method. As a reminder, GetOrAdd either returns the value for a key currently in the dictionary, or if that key doesn’t have a value, it adds a value for the key as dictated by either a TValue prov...
For .NET 4.5, we’ve invested quite a bit of effort into performance, and in particular for the Task Parallel Library (Joe Hoag wrote a good paper covering some of these improvements). We focused such effort on TPL because it is a core component used in async programming and at a foundational level for many libraries and applications.&nb...
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’t di...
We recently released a VS2010 sp1 QFE KB2650605 to solve a VB editor debugging problem. During VB web form debugging, VB web form may become un-editable if there are server tags inside. If you develop and debug VB web forms, you might be interested to download this QFE. http://connect.microsoft.com/VisualStudio/Downloads/DownloadDetails...
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 wrapper...
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 pumps.N...
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’s ...
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 thread. ...
Recently I’ve heard a number of folks asking about Task.Start, when and when not to use it, how it behaves,and so forth. I thought I’d answer some of those questions here in an attempt to clarify and put to rest any misconceptions about what it is and what it does.1. Question: When can I use Task.Start?The Start instance method ma...
