Mutexes, Condition Variables, and Synchronization Primitives

In the previous chapter we sorted out the thread lifecycle and RAII management — how to create threads and how to wait for them to finish safely. But threads alone are not enough: the moment several threads touch the same data, you need a coordination mechanism in place. 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 reader-writer lock (shared_mutex) for squeezing extra concurrency out of read-heavy, write-light workloads.

We will start with the basic usage of mutexes and RAII locks and pin down the difference between lock_guard and unique_lock; then dig into the wait semantics of condition_variable and get clear on the pitfalls you simply must master — spurious wakeups, lost wakeups, and friends; finally we will introduce C++17's shared_mutex and analyze where it applies and where its performance boundaries lie. Every step comes with compilable code examples and hands-on exercises.

In This Chapter

STARTFINISHmutex and RAII Locks→STARTFINISHDeadlock and Lock Ordering→STARTFINISHcondition_variable and Wait Semantics→STARTFINISHReader-Writer Locks and shared_mutex→STARTFINISHlatch, barrier, and semaphore→