来看一段代码：

void task1(mutex &m) {
    cout << "thread 1 init..." << endl;
    {
        std::unique_lock<mutex> lock(m);
        cout << "thread 1 getLock" << endl;
        sleep(5);
    }
    cout << "thread 1 freeLock" << endl;
    cout << "thread 1 exit..." << endl;
}


void task2(mutex &m) {
    cout << "thread 2 init..." << endl;
    {
        std::unique_lock<mutex> lock(m);
        cout << "thread 2 getLock" << endl;
    }
    cout << "thread 2 freeLock" << endl;
    cout << "thread 2 exit..." << endl;
}


int main() {
    mutex m;
    jthread t1(task1, std::ref(m));
    sleep(1);
    jthread t2(task2, std::ref(m));
}

代码的输出：

thread 1 init...
thread 1 getLock
thread 2 init...
thread 1 freeLock
thread 1 exit...
thread 2 getLock
thread 2 freeLock
thread 2 exit...

可以看出：线程在sleep的时候是不会释放锁的