.NET Parallel Programming

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

Task Parallel Library - .NET Parallel Programming

Building Async Coordination Primitives, Part 3: AsyncCountdownEvent

February 11, 2012 Feb 11, 2012 02/11/12
Stephen Toub - MSFT
In my last two posts, I discussed building AsyncManualResetEvent and AsyncAutoResetEvent coordination primitives.  In this post, I’ll build on that to create a simple AsyncCountdownEvent.A countdown event is an event that will allow waiters to complete after receiving a particular number of signals.  The “countdown&rdquo...

Building Async Coordination Primitives, Part 2: AsyncAutoResetEvent

February 11, 2012 Feb 11, 2012 02/11/12
Stephen Toub - MSFT
In my last post, I discussed building an asynchronous version of a manual-reset event.  This time, we’ll build an asynchronous version of an auto-reset event.A manual-reset event is transitioned to the signaled state when requested to do so (i.e. calling Set()), and then it remains in that state until it’s manually ...

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 ...

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&...

FAQ on Task.Start

January 14, 2012 Jan 14, 2012 01/14/12
Stephen Toub - MSFT
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 ...