C++多线程-chap2多线程通信和同步6

这里，只是记录自己的学习笔记。

顺便和大家分享多线程的基础知识。然后从入门到实战。有代码。

知识点来源：

https://edu.51cto.com/course/26869.html

scoped_lock C++17 用于多个互斥体的免死锁 RAII 封装器 类似lock
explicit scoped_lock(_Mutexes&... _Mtxes) : _MyMutexes(_Mtxes...) { // construct and lock
_STD lock(_Mtxes...);
} 
lock(mux1, mux2);
mutex mux1, mux2;
std::scoped_lock lock(mux1, mux2);

scoped_lock ，出了栈区会自动释放锁。因此，不必手动再调用 unlock() 解锁。

 1 #include 
 2 #include 
 3 #include <string> 
 4 #include 
 5 
 6 using namespace std;
 7 
 8 static mutex mux1;
 9 static mutex mux2;
10 
11 void TestScope1() {
12     //模拟死锁，停100ms 等另一个线程锁 mux2
13     this_thread::sleep_for(100ms);
14     cout << "begin mux1 lock " << this_thread::get_id() << endl;
15 //    mux1.lock();
16     cout << "begin mux2 lock " << this_thread::get_id() << endl;
17 //    mux2.lock();//死锁
18 
19     //C++11 
20     // lock(mux1, mux2);
21 
22     //C++17
23     // 出了栈区， 会将这里等待锁释放掉..所以不必再手动掉unlock()解锁
24     scoped_lock lock(mux1, mux2);//解决死锁
25 
26 
27     cout << "TestScope1 " << this_thread::get_id() << endl;
28     this_thread::sleep_for(1000ms);
29     //mux1.unlock();
30     //mux2.unlock();
31 }
32 
33 void TestScope2() {
34     cout << "Begin mux2 lock " << this_thread::get_id() << endl;
35     mux2.lock();
36     this_thread::sleep_for(500ms);
37     cout << "Begin mux1 lock " << this_thread::get_id() << endl;
38     mux1.lock();//死锁
39 
40     cout << "TestScope2 " << this_thread::get_id() << endl;
41     this_thread::sleep_for(1500ms);
42     mux1.unlock();
43     mux2.unlock();
44 }
45 
46 int main() {
47     {
48         //演示死锁情况
49         {
50             thread th(TestScope1);
51             th.detach();
52         }
53         {
54             thread th(TestScope2);
55             th.detach();
56         }
57     }
58 
59 
60     getchar();
61     return 0;
62 }