The Linux Programming Interface

30THREADS: THREAD SYNCHRONIZATION

In this chapter, we describe two tools that threads can use to synchronize their actions: mutexes and condition variables. Mutexes allow threads to synchronize their use of a shared resource, so that, for example, one thread doesn’t try to access a shared variable at the same time as another thread is modifying it. Condition variables perform a complementary task: they allow threads to inform each other that a shared variable (or other shared resource) has changed state.

30.1 Protecting Accesses to Shared Variables: Mutexes

One of the principal advantages of threads is that they can share information via global variables. However, this easy sharing comes at a cost: we must take care that multiple threads do not ...