1 #define _CRT_SECURE_NO_WARNINGS
2 #include <iostream>
3 #include <thread>
4 #include <future>
5 #include <vector>
6 #include <cstdlib>
7 #include <mutex>
8 using namespace std;
9 #define COUNT 1000000
10
11 //创建互斥量
12 mutex m;
13
14 //多线程计算加法
15 int add(vector<int> *arr,int start,int count)
16 {
17 static mutex m;//只会初始化一次
18 int sum(0);//保存结果
19 for (int i = 0; i < count; i++)
20 {
21 sum += (*arr)[start + i];
22 }
23 {
24 //锁定,离开作用区域,自动释放
25 lock_guard<mutex> lckg(m);
26 cout << "thread=" << this_thread::get_id()
27 << ",count=" << count
28 << ",sum=" << sum << endl;
29 }
30 return sum;
31 }
32
33 void main()
34 {
35 vector <int>data(COUNT);//数组,100万个数据
36 for (int i = 0; i < COUNT; i++)
37 {
38 data[i] = (i + 1) % 1000;// 赋值初始化
39 }
40
41 vector<future<int>> result;//结果数组,存放结果
42
43 int cpus = thread::hardware_concurrency();//CPU核心的个数
44
45 for (int i = 0; i < cpus * 2; i++)
46 {
47 int batch_each = COUNT / (cpus * 2);
48 //最后一个线程所计算的个数
49 if (i == (cpus * 2) - 1)
50 {
51 batch_each = COUNT - COUNT / (cpus * 2)*i;
52 }
53 //不断压入结果
54 result.push_back(async(add, &data, i*batch_each, batch_each));
55 //async直接返回future类型结果
56 }
57
58 //汇总
59 int lastresult(0);
60 for (int i = 0;i<result.size();i++)
61 {
62 lastresult += result[i].get();//汇总结果
63 }
64 cout << "结果=" << lastresult << endl;
65
66 cin.get();
67 }
