A spurious wakeup happens when a waiting thread wakes up even though no thread actually signaled it, and the condition it was waiting for is still false. It sounds unlikely, but many threading APIs explicitly allow it, which means your code must handle it correctly.

This chapter explores what spurious wakeup is, why it exists, what causes them at the operating system and hardware level, and how to write defensive code that handles them correctly.

What is a Spurious Wakeup?