From time to time, I receive questions from developers which highlight either a need for more information about the new “async” and “await” keywords in C# and Visual Basic. I’ve been cataloguing these questions, and I thought I’d take this opportunity to share my answers to them.Conceptual Overviewhttps://msdn.co...

Developers familiar with parallel programming are also familiar with a wide range of potential problems that can occur when practicing the art.  One of the most well-known issues is “deadlock,” where two or more operations are waiting on each other to complete in a manner such that none of them will be able to complete.I’ve r...

In .NET 4.5 Beta, the Stream class provides multiple virtual methods related to reading and writing: As a developer deriving from Stream, it’s helpful to understand what the base implementations do and when you can and should override them.Read, Write, FlushThe Read, Write, and Flush methods are the core synchronous mechanisms...

I get this question a lot: “Task implements IDisposable and exposes a Dispose method.  Does that mean I should dispose of all of my tasks?” SummaryHere’s my short answer to this question: “No.  Don’t bother disposing of your tasks.”Here’s my medium-length answer: “No.  Don&rsquo...

Lately I’ve received several questions along the lines of the following, which I typically summarize as “async over sync”: In my library, I have a method “public T Foo();”.  I’m considering exposing an asynchronous method that would simply wrap the synchronous one, e.g. “public Task<T> FooAsync...

Every now and then, I get this question: “is it ok to use nested Parallel.For loops?” The short answer is “yes.”  As is often the case, the longer answer is, well, longer. Typically when folks ask this question, they’re concerned about one of two things.  First, they’re concerned that each nested loop will assume it “owns the machine” and will thu...

Are you using the new System.Threading.Tasks.Dataflow.dll library, either from its CTPs or from the .NET 4.5 Developer Preview or Beta?  We'd love to hear about it, and if you have time, what your experiences have been (good or bad).  What kind of solution are you building, and how are you using TPL Dataflow in it?  Has the library h...

After my previous post, I received several emails and comments from folks asking why I chose to implement ForEachAsync the way I did.  My goal with that post wasn’t to prescribe a particular approach to iteration, but rather to answer a question I’d received… obviously, however, I didn’t provide enough background. Let ...

Jon Skeet recently asked me how I might go about implementing the following “asynchronous ForEach” behavior: Given what we now know about SemaphoreSlim from my previous post, here’s one way to achieve this: public static Task ForEachAsync<TSource, TResult>(     this IEnumerable<TSource> ...

The C# and Visual Basic compilers implement support for async/await by generating code that utilizes some specific types in the underlying framework.  These types include the “awaiters” used to await things (like Tasks) as well as the “builders” used in handling the lifetime of an async method’s invocation. With t...