CHAPTER 19 MULTITHREADED, PARALLEL, AND ASYNC PROGRAMMING
That wraps up your investigation of the System.Threading namespace. To be sure, understanding
the topics presented thus far in the chapter (especially during our examination of concurrency issues)
will be extremely valuable when creating a multithreaded application. Given this foundation, we will
now turn our attention to a number of new thread-centric topics which are only available under .NET 4.0
and higher. To begin, we will examine the role of an alternative threading model, termed the TPL.
Parallel Programming Using the Task Parallel Library
At this point in the chapter, you have examined two programming techniques (using asynchronous
delegates and via the members of System.Threading) that allow you to build multithreaded software.
Recall that both of these approaches will work under any version of the .NET platform.
Beginning with the release of .NET 4.0, Microsoft introduced a new approach to multithreaded
application development using a parallel programming library termed the Task Parallel Library (TPL).
Using the types of System.Threading.Tasks, you can build fine-grained, scalable parallel code without
having to work directly with threads or the thread pool.
This is not to say, however, that you will not use the types of System.Threading when you make use
of the TPL. In reality, these two threading toolkits can work together quite naturally. This is especially
true in that the System.Threading namespace still provides a majority of the synchronization primitives
we examined previously (Monitor, Interlocked, and so forth). This being said, you will quite likely find
that you will favor working with the TPL rather than the original System.Threading namespace, given
that the same set of tasks can be performed in a more straightforward manner.
Note On a related note, be aware that the new .NET 4.5 C# async and await keywords make use of various
members of the System.Threading.Tasks namespace.
The System.Threading.Tasks Namespace
Collectively speaking, the types of System.Threading.Tasks are referred to as the Task Parallel Library, or
TPL. The TPL will automatically distribute your application’s workload across available CPUs
dynamically, using the CLR thread pool. The TPL handles the partitioning of the work, thread
scheduling, state management, and other low-level details. The end result is that you can maximize the
performance of your .NET applications, while being shielded from many of complexities of directly
working with threads (see Figure 19-3).
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