1. condition_variable使用步骤如下：
2. 创建一个condition_variable对象
3. 创建一个互斥锁mutex对象，用来保护共享资源的访问
4. 在需要等待条件变量的地方，使用unique_lock<mutec>对象锁定互斥锁并调用condition_variable::wait()、condition_variable::wait_for()或condition_variable::wait_until()函数等条件变量
5. 在其他线程中通知等待的线程时，调用condition_variable::notify_one()或condition_variable::notify_all()函数通知等待的线程

生产者与消费者模型

代码示例：

#include<iostream>
using namespace std;
#include <thread>
#include <mutex>
#include <condition_variable>
#include <queue>mutex g_mutex;
condition_variable g_cv;
queue<int>g_queue;void Producer() {for (int i = 0; i < 10; i++){unique_lock<mutex>lock(g_mutex);g_queue.push(i);cout << "Producer: prodeced " << i << endl;g_cv.notify_one();this_thread::sleep_for(chrono::milliseconds(100));}
}void Consumer() {while (true){unique_lock<mutex>lock(g_mutex);g_cv.wait(lock, []() {return !g_queue.empty(); });int value = g_queue.front();g_queue.pop();cout << "Consumer: consumed " << value << endl;}
}int main()
{thread producer_thread(Producer);thread consumer_thread(Consumer);producer_thread.join();consumer_thread.join();system("pause");system("cls");
}