The Evolution of Threads and I/O in Windows

My latest column for MSDN Magazine is now available online as well as in print.

When starting a new project, do you ask yourself whether your program will be compute-bound or I/O-bound? You should. I’ve found that in most cases it’s either one or the other. You might be working on an analytics library that’s handed a pile of data and keeps a bunch of processors busy while crunching it all down to a set of aggregates. Alternatively, your code might spend most of its time waiting for stuff to happen, for data to arrive over the network, a user to click on something or perform some complex six-fingered gesture. In this case, the threads in your program aren’t doing very much. Sure, there are cases where programs are heavy both on I/O and computation. The SQL Server database engine comes to mind, but that’s less typical of today’s computer programming. More often than not, your program is tasked with coordinating the work of others. It might be a Web server or client communicating with a SQL database, pushing some computation to the GPU or presenting some content for the user to interact with. Given all of these different scenarios, how do you decide what threading capabilities your program requires and what concurrency building blocks are necessary or useful? Well, that’s a tough question to answer generally and something you’ll need to analyze as you approach a new project. It’s helpful, however, to understand the evolution of threading in Windows and C++ so you can make an informed decision based on the practical choices that are available.

This article carries on where I left off in November with The Evolution of Synchronization in Windows and C++.

You can find links to more of my articles here.

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