我有几个线程,我需要抓住他们都完成工作的那一刻.
怎么做?
for (int i = 1; i < 3; i++) {
std::thread threads1(countFile, i);
i++;
std::thread threads2(countFile, i);
threads1.detach();
threads2.detach();
}
// wait until all the threads run out---
// to do next function ob object which uses by threads--
最佳答案 考虑在for-block之外创建std :: thread对象并调用join()而不是detach():
// empty (no threads associated to them yet)
std::array<std::thread, 2> threads1, threads2;
for (int i = 0; i < 2; i++) {
threads1[i] = std::thread(countFile, i+1); // create thread
i++;
threads2[i] = std::thread(countFile, i+1); // create thread
}
// ...
// join on all of them
for (int i = 0; i < 2; i++) {
threads1[i].join();
threads2[i].join();
}
// at this point all those threads have finished
不调用detach()意味着必须在调用std :: thread对象的析构函数之前调用join()(无论线程是否已经完成).
出于这个原因,我将std :: thread对象放在for-block之外.否则,必须在for-block内调用join().