.NET Parallel Programming

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

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...

C# memory model articles

December 14, 2012 Dec 14, 2012 12/14/12

Stephen Toub - MSFT

Igor Ostrovsky is one of the minds behind the parallel programming support in the .NET Framework. Igor's recently written a great set of articles for MSDN Magazine to cover "The C# Memory Model in Theory and Practice". Part 1 is available now in the December 2012 issue, and it's a great read...

PLINQ and Int32.MaxValue

November 16, 2012 Nov 16, 2012 11/16/12

Stephen Toub - MSFT

In both .NET 4 and .NET 4.5, PLINQ supports enumerables with up to Int32.MaxValue elements. Beyond that limit, PLINQ will throw an overflow exception. LINQ to Objects itself has this limitation with certain query operators (such as the indexed Select operator which counts the elements processed), but PLINQ has it with more.This ...

How do I cancel non-cancelable async operations?

October 5, 2012 Oct 5, 2012 10/5/12

Stephen Toub - MSFT

This is a question I hear relatively frequently: “I have an async operation that’s not cancelable. How do I cancel it?” The construction of the question often makes me chuckle, but I understand and appreciate what’s really being asked. The developer typically isn’t asking how to cancel the operation...

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 ...