A Simple Approach: Just Yield, Baby

Hardware support got us pretty far: working locks, and even (as with the case of the ticket lock) fairness in lock acquisition. However, we still have a problem: what to do when a context switch occurs in a critical section, and threads start to spin endlessly, waiting for the interrupted (lock-holding) thread to be run again?

Lock with test-and-set and yield

Our first try is a simple and friendly approach: when you are going to spin, instead give up the CPU to another thread. As Al Davis might say, “just yield, baby!”“Just Win, Baby: Al Davis and His Raiders” by Glenn Dickey. Harcourt, 1991. The book about Al Davis and his famous quote. Or, we suppose, the book is more about Al Davis and the Raiders, and not so much the quote. To be clear: we are not recommending this book, we just needed a citation.. The code excerpt below shows the approach.