Worker Threads

Worker threads are an elegant solution to a number of problems about concurrent processing; for example, the need to keep the GUI active while a computation is being performed. This essay addresses some of the issues of using worker threads. A companion essay talks about some techniques dealing with user-interface threads.

Why Worker Threads?

Consider a simple implementation of a program. For our purposes, the program has the task of inverting the color of every pixel of an image, just because we sometimes need a concrete example to illustrate techniques. For the sake of our example, we will assume that the image being processed is 10 megapixels of 24-bit color.