How do I use condition variables in threading?

How do I use condition variables in threading?

Condition variables are synchronization primitives that allow threads to wait until a particular condition occurs. They are often used with mutexes to avoid race conditions.

Can you give me an example of how to implement a condition variable?

Sure! Here's a simple example in C++:

#include <iostream>
#include <thread>
#include <mutex>
#include <condition_variable>

std::mutex mtx;
std::condition_variable cv;
bool ready = false;

void worker() {
    std::unique_lock<std::mutex> lock(mtx);
    while (!ready) {
        cv.wait(lock);
    }
    std::cout << "Worker thread is running!" << std::endl;
}

int main() {
    std::thread t(worker);
    std::this_thread::sleep_for(std::chrono::seconds(1));
    {
        std::lock_guard<std::mutex> lock(mtx);
        ready = true;
    }
    cv.notify_one();
    t.join();
    return 0;
}

What happens if I forget to notify the condition variable?

If you forget to notify the condition variable, the waiting thread will remain blocked indefinitely, leading to a deadlock situation.

Are there any alternatives to condition variables?

Yes, alternatives include using semaphores, message queues, or even higher-level abstractions like futures and promises.