Author:DriverMonkey

Mail:bookworepeng@Hotmail.com

Phone:13410905075

QQ:196568501

测试环境：Win7 64 bit

编译器：gcc 4.81

测试代码-

/*********************************************************************************
 Copyright (C), 1988-1999, drvivermonkey. Co., Ltd.
 File name: 
 Author: Driver Monkey
 Version: 
 Mail:bookworepeng@hotmail.com
 Date: 2014.04.02
 Description:  Test std lib automic_flag
 *********************************************************************************/
#include 
   
           // std::cout
#include 
    
      // std::atomic_flag #include 
     
       // std::thread #include 
      
        // std::vector #include 
       
         // std::stringstream using namespace std; atomic_flag lock_stream = ATOMIC_FLAG_INIT; stringstream stream; void append_number(int x) { while (lock_stream.test_and_set()) { ; } stream << "thread #" << x << '\n'; lock_stream.clear(); } int main () { std::vector
        
          threads; for (int i=1; i<=10; ++i) { threads.push_back(thread(append_number,i));//create thread } for (auto& th : threads) { th.join();// wait thread return } cout << stream.str(); return 0; } 
        
       
      
     
    
   

以上代码运行结果：

如果屏蔽掉 //while (lock_stream.test_and_set()) 这一句代码运行结果：< http://www.2cto.com/kf/ware/vc/" target="_blank" class="keylink">vcD4KPHA+Cjxicj4KPC9wPgo8cD4KPGltZyBzcmM9"https://www.cppentry.com/upload_files/article/49/1_djrr2__.jpg" alt="">

总结：

第一组代码线程内部加锁部分代码整个运行顺序和创建顺序一致。

第二组代码线程内部代码整个穿插运行的，没有先后顺序

对比两组代码运行结果可以看出加锁成功