Summary

Concurrent programming includes all the necessary tools and techniques to have multiple tasks or process running at the same time in a computer, communicating and synchronizing between them without data loss or inconsistency.

We started this chapter by introducing the basic concepts of concurrency. You must know and understand terms such as concurrency, parallelism, and synchronization to fully understand the examples of this book. However, concurrency can generate some problems, such as data race conditions, deadlocks, livelocks, and others. You must also know the potential problems of a concurrent application. It will help you identify and solve these problems.

We also explained a simple methodology of five steps introduced by Intel to convert a sequential algorithm into a concurrent one and showed you some concurrency design patterns implemented in the Java language and some tips to take into account when you implement a concurrent application.

Finally, we explained briefly the components of the Java concurrency API. It's a very rich API with low- and very high-level mechanisms that allow you to implement powerful concurrency applications easily. We also described the Java memory model, which determines how concurrent applications manage the memory and the execution order of the instructions internally.

In the next chapter, you will learn how to implement applications that use a lot of threads using the executor framework. This allows you to execute a big number of threads by controlling the resources you use and reducing the overhead introduced by thread creation (it reuses Thread objects to execute different tasks).