Mutexes, Condition Variables, and Synchronization Primitives
In the previous chapter, we explored the thread lifecycle and RAII management—learning how to create threads and safely wait for them to finish. But threads alone are not enough; when multiple threads access the same data, we need a coordination mechanism. This chapter focuses on the most fundamental synchronization primitives in the C++ standard library: the mutex for protecting critical sections, the condition_variable for wait-notify coordination between threads, and the shared_mutex for concurrency optimization in read-heavy, write-light scenarios.
We will start with the basic usage of mutexes and RAII locks, understanding the differences between lock_guard and unique_lock. Then we will dive into the wait semantics of condition_variable, clarifying essential pitfalls like spurious wakeups and lost wakeups. Finally, we will introduce the C++17 shared_mutex, analyzing its applicable scenarios and performance boundaries. Every step is accompanied by compilable code examples and practical exercises.