等待C++中的所有线程

Question

我在C++中使用构造"线程",我在递归函数中创建了一个可变数量的线程.我希望主线程等待所有这些.没有WaitForMultipleObjects我怎么能这样做？

Answer 1

看看cplusplus 中的例子.它们在向量中存储带有push_back()的线程.最后你有连接循环.

std::vector<std::thread> threads;
//create threads
for (int i=1; i<=10; ++i)
    threads.emplace_back(std::thread(increase_global,1000));
//wait for them to complete
for (auto& th : threads) 
    th.join();

Answer 2

使用原子变量作为计数器，启动新线程时增加变量，线程完成后在线程中减少计数器。

int main() {
    mutex m;
    condition_variable cv;
    atomic<int> counter = 0;

    // .... in your recursive call
    // increase counter when launching thread.
    counter++;
    thread t([](){
        // do whatever
        lock_guard<mutex> lk(m);
        counter--;
        cv.notify_all();
    });
    t.detach(); // no need to join anymore.
    // .... end recursive call

    unique_lock<mutex> lock(m);
    cv.wait(lock, [](){ return counter == 0; });
}