The Little Book of Semaphores is a free textbook that introduces the principles of synchronization for concurrent programming.
In most computer science curricula, synchronization is a module in an Operating Systems class. OS textbooks present a standard set of problems with a standard set of solutions, but most students don't get a good understanding of the material or the ability to solve similar problems.
The approach of this book is to identify patterns that are useful for a variety of synchronization problems and then show how they can be assembled into solutions. After each problem, the book offers a hint before showing a solution, giving students a better chance of discovering solutions on their own.
The book covers the classical problems, including "Readers-writers," "Producer-consumer", and "Dining Philosophers." In addition, it collects a number of not-so-classical problems, some written by the author and some by other teachers and textbook writers. Readers are invited to create and submit new problems.
This open book is licensed under a Creative Commons License (CC BY-NC-SA). You can download The Little Book of Semaphores ebook for free in PDF format (1.2 MB).
Table of Contents
Basic synchronization patterns
Classical synchronization problems
Less classical synchronization problems
Not remotely classical problems
Synchronization in Python
Synchronization in C
Cleaning up Python threads
Cleaning up POSIX threads