Summary

You discovered how a QThread class works and learned how to efficiently use tools provided by Qt to create a powerful multi-threaded application. Your Mandelbrot application is able to use all cores of your CPU to compute a picture quickly.

Creating a multi-threaded application presents a lot of pitfalls (deadlock, event loop flood, orphan threads, overhead, and so on). The application architecture is important. If you are able to isolate the heavy code that you want to parallelize, everything should go well. Nevertheless, the user experience is of primary importance; you will sometimes have to accept a little overhead if your application gives the user a smoother feeling.

In the next chapter, we will see several ways to implement an IPC (Inter-Process Communication) between applications. The project example will enhance your current Mandelbrot application with a TCP/IP socket system. So the Mandelbrot generator will compute pictures over several CPU cores from multiple computers!