Summary

Semaphores are a powerful and flexible primitive for writing concurrent programs. Some programmers use them exclusively, shunning locks and condition variables, due to their simplicity and utility.

In this chapter, we have presented just a few classic problems and solutions. If you are interested in finding out more, there are many other materials you can reference. One great (and free reference) is Allen Downey’s book on concurrency and programming with semaphores. This book has lots of puzzles you can work on to improve your understanding of both semaphores in specific and concurrency in general. Becoming a real concurrency expert takes years of effort; going beyond what you learn in this course is undoubtedly the key to mastering such a topic.