C++学习笔记 43 C++11 std::async 异步多线程

一、实例代码

问题 无论std::async调用了多少次，只额外单启动了一个线程，并且串行执行！待解惑

#include<iostream>
#include<thread>
#include <chrono>
#include <future>

//锁
static std::mutex s_mutex;

static void sleepMine(int i) {
	std::thread::id threadId = std::this_thread::get_id();
	//std::lock_guard<std::mutex> loock(s_mutex);
	std::cout << threadId << " Hello world" << i << " start." << std::endl;
	std::this_thread::sleep_for(std::chrono::seconds(i));
	std::cout << threadId << " Hello world" << i << " end." << std::endl;
}

int main() {
	/*for (int i = 1; i <= 5; i++) {
		std::thread::id threadId = std::this_thread::get_id();
		std::cout << threadId << " Main " << i << " end." << std::endl;
		std::async(std::launch::async, sleepMine, i);
	}*/
	std::async(std::launch::deferred, sleepMine, 1).get();
	std::async(std::launch::deferred, sleepMine, 2).get();
	std::async(std::launch::deferred, sleepMine, 3).get();
	std::cin.get();
}