[C++11 多线程同步] --- 条件变量的那些坑条件变量信号丢失和条件变量虚假唤醒(spurious wakeup)

Posted 2022-12-04 Overboom

1 条件变量的信号丢失

1.1 条件变量的信号丢失场景重现

拿生产者和消费者模型举例，看一段示例代码：

#include <iostream>
#include <vector>
#include <mutex>
#include <condition_variable>
#include <thread>
#include <unistd.h>

std::mutex mutex;
std::condition_variable cv;
std::vector<int> vec;

void consumer() 

	sleep(1);
    std::unique_lock<std::mutex> lock(mutex);
    std::cout << "blocking on wait" << std::endl;
    cv.wait(lock);
    std::cout << "executed wait" << std::endl;
    std::cout << "consume " << vec.size() << "\\n";


void produce() 
    std::unique_lock<std::mutex> lock(mutex);
    vec.push_back(1);
    cv.notify_all();
    std::cout << "produce" << std::endl;


int main() 
    std::thread consumers, producers;
    consumers = std::thread(consu