CPP多线程实现并行计算

来源：互联网发布：java.util.list.sort 编辑：程序博客网时间：2024/05/11 00:22
#include <iostream>#include <mutex>#include <future>#include <thread>#include <chrono>#include <vector>#include <cstdlib>using namespace std;#define COUNT 5000000long long  add(vector <long long >*arr, long long  start, long long count){static mutex m;//仅仅初始化一次int sum(0);//保存结果for (long long i = 0; i < count; i++){sum += (*arr)[start+i];//根据下标  累加}{lock_guard<mutex>lckg(m);//锁定cout <<"线程ID："<< this_thread::get_id() <<"count="<<count<<"sum="<<sum<< endl;}return sum;}void main(){vector<long long>myint(COUNT);//开辟数组大小for (int i = 0; i < COUNT; i++)//填充数据  赋值{myint[i] = (i+1)%1000;//限定数据范围 0~999//cout << myint[i] << "";}//future < vector<long long>>abc ;vector<future<long long >>result;//实现并行计算 获取CPU核心个数   创建线程必须为CPU核心的个数long long  cpus = thread::hardware_concurrency();cout << "cpu核心个数：" << cpus << endl;//启动线程   存储结果   使用线程分块for (long long i = 0; i < cpus * 2; i++){//<span style="font-family: Arial, Helvetica, sans-serif;">//线程切割     </span>线程分块long long  batch_each = COUNT / (cpus * 2);if (i == cpus * 2-1){batch_each = COUNT - COUNT / (cpus * 2)*i;//让最后一个线程承载多点}result.push_back(async(add,&myint,i*batch_each,batch_each));//压入数据}//分数据long long  lastresult(0);//最终结果//汇总数据for (long long i = 0; i < cpus * 2; i++){lastresult += result[i].get();//累加}cout << "lastresult ="<< lastresult << endl;cin.get();}
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