.NET Parallel Programming

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

Cancellation in Parallel Extensions

One of the great features that crosses all of Parallel Extensions types is a consistent approach to cancellation (see https://blogs.msdn.com/pfxteam/archive/2009/05/22/9635790.aspx). In this post we explore some of the ways cancellation is used in Parallel Extensions and explain the guidance we developed. The new cancellation system is a ...

How PLINQ processes an IEnumerable on multiple cores

As Ed Essey explained in Partitioning in PLINQ, partitioning is an important step in PLINQ execution. Partitioning splits up a single input sequence into multiple sequences that can be processed in parallel. This post further explains chunk partitioning, the most general partitioning scheme that works on any IEnumerable<T>.Chunk ...

Tasks and the APM Pattern

The Asynchronous Programming Model (APM) in the .NET Framework has been around since .NET 1.0 and is the most common pattern for asynchrony in the Framework.  Even if you’re not familiar with the name, you’re likely familiar with the core of the pattern.  For a given synchronous operation Xyz, the asynchronous version ...

Achieving Speedups with Small Parallel Loop Bodies

The Parallel class represents a significant advancement in parallelizing managed loops.  For many common scenarios, it just works, resulting in terrific speedups.  However, while ideally Parallel.For could be all things to all people, such things rarely work out, and we’ve had to prioritize certain scenarios over others.One ...

Mechanisms for Creating Tasks

The core entity in the Task Parallel Library around which everything else revolves is System.Threading.Tasks.Task.  The most common way of creating a Task will be through the StartNew method on the TaskFactory class, a default instance of which is exposed through a static property on Task, e.g. var t = Task.Factory.StartNew(() => { &...

Tasks and Unhandled Exceptions

Prior to the .NET Framework 2.0, unhandled exceptions were largely ignored by the runtime.  For example, if a work item queued to the ThreadPool threw an exception that went unhandled by that work item, the ThreadPool would eat that exception and continue on its merry way.  Similarly, if a finalizer running on the finalizer thread ...

ParallelOptions.MaxDegreeOfParallelism vs PLINQ’s WithDegreeOfParallelism

We exert a good deal of effort ensuring that the APIs we provide are consistent within Parallel Extensions as well as with the rest of the .NET Framework.  This is from many angles, including behavior and general design, but also naming.  So when there are slight differences in naming, it raises questions.One occurrence of such a ...

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