.NET Parallel Programming

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

Async - .NET Parallel Programming

Tasks, Monads, and LINQ

April 3, 2013 Apr 3, 2013 04/3/13
Stephen Toub - MSFT
A few years back, Wes Dyer wrote a great post on monads, and more recently, Eric Lippert wrote a terrific blog series exploring monads and C#. In that series, Eric alluded to Task<TResult> several times, so I thought I’d share a few related thoughts on Task<TResult> and the async/await keywords.As both Wes and Eric highlight...

“Invoke the method with await”… ugh!

March 13, 2013 Mar 13, 2013 03/13/13
Stephen Toub - MSFT
I can be a bit sensitive when it comes to language and how concepts are conveyed.  I think it’s important to be accurate, even if not precise, when describing what something is or how to use it, as otherwise the folks to whom you’re communicating can easily form the wrong mental model for that thing.  Having a good mental...

MVP Summit presentation on async

February 20, 2013 Feb 20, 2013 02/20/13
Stephen Toub - MSFT
Lucian Wischik and I presented an "async clinic" at the MVP Summit in Bellevue this week.  The async/await keywords in C# and Visual Basic drastically simplify asynchronous programming, but that of course doesn't mean that using them is without any gotchas: the goal of the discussion was to highlight some of the key areas in ...

Psychic Debugging of Async Methods

January 28, 2013 Jan 28, 2013 01/28/13
Stephen Toub - MSFT
These days it’s not uncommon for me to receive an email or read a forum post from someone concerned about a problem they’re experiencing with an async method they’ve written, and they’re seeking help debugging the issue.  Sometimes plenty of information about the bug is conveyed, but other times the communication ...

Cooperatively pausing async methods

January 13, 2013 Jan 13, 2013 01/13/13
Stephen Toub - MSFT
Recently I was writing an app that processed a bunch of files asynchronously.  As with the Windows copy file dialog, I wanted to be able to provide the user with a button that would pause the processing operation.To achieve that, I implemented a simple mechanism that would allow me to pass a “pause token” into the async method...

Forking in async methods

September 11, 2012 Sep 11, 2012 09/11/12
Stephen Toub - MSFT
Given that .NET 4.5 has only recently been released in its final form, it’s not surprising that many folks are still very new to the async/await keywords and have misconceptions about what they are and what they do (I’ve tried to clarify some of these in this Async/Await FAQ).  One of the more common misconceptions is that a ...

Implementing Then with Await

August 15, 2012 Aug 15, 2012 08/15/12
Stephen Toub - MSFT
In a post a while ago, I talked about sequential composition of asynchronous operations.  Now that we have the async/await keywords in C# and Visual Basic, such composition is trivial, and async/await are indeed the recommended way to achieve such composition with these languages.However, in that post I also described a few “Then&...

Processing tasks as they complete

August 2, 2012 Aug 2, 2012 08/2/12
Stephen Toub - MSFT
Recently I’ve had several folks ask me about how to process the results of tasks as those tasks complete.A developer will have multiple tasks representing asynchronous operations they’ve initiated, and they want to process the results of these tasks, e.g. List<Task<T>> tasks = …; foreach(var t in tasks...