CODEWITHSUNDEEP
c++multithreadingstlthread-safety
gmmo
gmmo

Reputation: 2791

do condition variables unlock their mutex?

I am working with condition variables and I am assuming they unlock their associated mutex on wait. Otherwise, the mutex would never be released. Yet, I can't find this information on any documentation. Consider the following code:

std::condition_variable consumerWakeMeUp;
std::mutex queueMutex;
// this locks the mutex
std::unique_lock<std::mutex> lk(queueMutex);
// going to sleep now
consumerWakeMeUp.wait(lk);

Does the "consumerWakeMeUp.wait(lk)" unlock the mutex? It must I assume otherwise the thread would hand on that mutext forever. But if anyone knows more the details I'd appreciate the input.

thank you.

Upvotes: 4

Views: 2010

Answers (1)

gmmo
gmmo

Reputation: 2791

never mind

"Atomically releases lock, blocks the current executing thread, and adds it to the list of threads waiting on *this. The thread will be unblocked when notify_all() or notify_one() is executed. It may also be unblocked spuriously. When unblocked, regardless of the reason, lock is reacquired and wait exits. If this function exits via exception, lock is also reacquired. (until C++14)"

Upvotes: 3

Related Questions