C ++连接多个线程 [英] C++ Join multiple threads

问题描述

我想做一个for循环，创建更多线程.

I would like to do a for-loop which creates more threads.

我尝试过:

int i;
for (i = 0; i < 10; i++) {
    thread t1(nThre);
    t1.join();
    cout << "Joined thread n'" << i << '\n';
}

但是它不起作用.依次调用nThre(这是一个简单的void例程).

But it does not work. nThre is called sequentially (it is a simple void routine).

我还问我是否可以使用预增量，因为i只是一个int，所以: ++i插入了i++，应该会表现得更好.

I'm also asking if I can use a pre-increment as i is just an int, so: ++i insted of i++, which should be more performant.

推荐答案

您的问题是您启动了一个线程，并在启动下一个线程之前将其加入.您应该这样做:

Your problem is that you start a thread, and join it before starting the next one. You should do like this :

int i;
vector<thread> threads;

for (i = 0; i < 10; i++) {
    threads.push_back(thread(nThre));
    cout << "Started thread n'" << i << "\n";
}

for (i = 0; i < 10; i++) {
    threads[i].join();
    cout << "Joined thread n'" << i << "\n";
}

首先，启动所有线程，然后等待直到完成.

First, you start all your threads, then you wait until they are finished.

对于i++和++i之间的差异，由于i是整数，因此在这里没有区别.请参阅此答案了解更多信息.

For the difference between i++ and ++i, since i is a integer, it makes no difference here. See this answer for more details.

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