通过容器创建多个线程
- #include <vector>
- #include <iostream>
- #include <thread>
- void printTest(int num)
- {
- std::cout << "子线程:" << num << "启动" << std::endl;
- std::cout << "子线程:" << num << "结束" << std::endl;
- }
- int main()
- {
- std::vector<std::thread* > test;
- for (int i = 0; i < 10; i++)
- {
- test.push_back(new std::thread(printTest, i));
- }
- for (auto& pmove : test)
- {
- pmove->join();
- }
- std::cout << "主线程" << std::endl;
- return 0;
- }
数据共享问题分析只读数据:稳定安全,不需要特殊处理,直接读即可
- #include <vector>
- #include <iostream>
- #include <thread>
- std::vector<int> g_data={ 1,2,3 };
- void printTest(int num)
- {
- std::cout << "子线程:" << num << "读操作" << std::endl;
- for (auto pmove : g_data)
- {
- std::cout << pmove << std::endl;
- }
- }
- int main()
- {
- std::vector<std::thread* > test;
- for (int i = 0; i < 10; i++)
- {
- test.push_back(new std::thread(printTest, i));
- }
- for (auto& pmove : test)
- {
- pmove->join();
- }
- std::cout << "主线程" << std::endl;
- return 0;
- }
有读有写:需要做特别处理(写只做写,读只做读操作,保持共享数据只有唯一操作),不然会引发崩溃
- #include <list>
- #include <iostream>
- #include <thread>
- class SeaKing
- {
- public:
- void makeFriend()
- {
- for (int i = 0; i < 100000; i++)
- {
- std::cout << "增加一个" << std::endl;
- mm.push_back(i);
- }
- }
- void breakUp()
- {
- for (int i = 0; i < 100000; i++)
- {
- if (!mm.empty())
- {
- std::cout << "减少一个:"<<mm.front() << std::endl;
- mm.pop_front();
- }
- else
- {
- std::cout << "已空" << std::endl;
- }
- }
- }
- protected:
- std::list<int> mm;
- };
- int main()
- {
- SeaKing man;
- std::thread t1(&SeaKing::makeFriend, &man);
- std::thread t2(&SeaKing::breakUp, &man);
- t1.join();
- t2.join();
- return 0;
- }
- //以上程序会异常退出
加锁的方式解决数据共享问题互斥量mutex: 互斥量可以理解为锁,他是一个mutex类的对象通过调用成员函数lock函数进行加锁通过调用成员函数unlock函数进行解锁
- #include <list>
- #include <iostream>
- #include <thread>
- #include <mutex> //1.包含头文件
- class SeaKing
- {
- public:
- void makeFriend()
- {
- for (int i = 0; i < 100000; i++)
- {
- m_mutex.lock();
- std::cout << "增加一个" << std::endl;
- mm.push_back(i);
- m_mutex.unlock();
- }
- }
- bool readInfo()
- {
- m_mutex.lock(); //2.加锁
- if (!mm.empty())
- {
- std::cout << "减少一个:" << mm.front() << std::endl;
- mm.pop_front();
- m_mutex.unlock();
- return true;
- }
- m_mutex.unlock();
- return false;
- }
- void breakUp()
- {
- for (int i = 0; i < 100000; i++)
- {
- int result = readInfo();
- if (result == false)
- {
- std::cout << "已空" << std::endl;
- }
- }
- }
- protected:
- std::list<int> mm;
- std::mutex m_mutex; //创建互斥量对象
- };
- int main()
- {
- SeaKing man;
- std::thread t1(&SeaKing::makeFriend, &man);
- std::thread t2(&SeaKing::breakUp, &man);
- t1.join();
- t2.join();
- return 0;
- }
注意:lock函数与unlock都是成对出现,如果lock了没有调用unlock会引发异常,abort终止程序通过lock_guard加锁。
- #include <list>
- #include <iostream>
- #include <thread>
- #include <mutex>
- class SeaKing
- {
- public:
- void makeFriend()
- {
- std::lock_guard<std::mutex> sbguard(m_mutex);
- for (int i = 0; i < 100000; i++)
- {
- std::cout << "增加一个" << std::endl;
- mm.push_back(i);
- }
- }
- bool readInfo()
- {
- std::lock_guard<std::mutex> sbguard(m_mutex);
- if (!mm.empty())
- {
- std::cout << "减少一个:" << mm.front() << std::endl;
- mm.pop_front();
- return true;
- }
- return false;
- }
- void breakUp()
- {
- for (int i = 0; i < 100000; i++)
- {
- int result = readInfo();
- if (result == false)
- {
- std::cout << "已空" << std::endl;
- }
- }
- }
- protected:
- std::list<int> mm;
- std::mutex m_mutex;
- };
- int main()
- {
- SeaKing man;
- std::thread t1(&SeaKing::makeFriend, &man);
- std::thread t2(&SeaKing::breakUp, &man);
- t1.join();
- t2.join();
- return 0;
- }
其实lock_guard 在构造函数中进行lock,在析构函数中进行unlock,本质上还是lock与unlock操作。