c++ - VS2015中的C++局部静态变量初始化线程安全吗

根据https://msdn.microsoft.com/en-us/library/hh567368.aspx

魔术静电(http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2008/n2660.htm)
在VS2015上受支持

但是在调试x64 Vs2015 Update 3中测试以下代码

#include "stdafx.h"
#include <iostream>
#include <windows.h>
#include <tchar.h>

#define MAX_THREADS 5

class Sleeper
{
public:
    Sleeper()
    {
        std::cout << "Sleeper \n";
        Sleep(100000);
    }
};

DWORD WINAPI MyThreadFunction(LPVOID lpParam)
{
    std::cout << "Sleeper Start" << (int)lpParam << "\n";
    static Sleeper s;
    std::cout << "Sleeper Done" << (int)lpParam << "\n";
    return 0;
}

int main(int, char**)
{
    DWORD   dwThreadIdArray[MAX_THREADS];
    HANDLE  hThreadArray[MAX_THREADS];

    // Create MAX_THREADS worker threads.

    for (int i = 0; i<MAX_THREADS; i++)
    {
        // Create the thread to begin execution on its own.
        hThreadArray[i] = CreateThread(
            NULL,                   // default security attributes
            0,                      // use default stack size
            MyThreadFunction,      // thread function name
            (LPVOID)i,               // argument to thread function
            0,                     // use default creation flags
            &dwThreadIdArray[i]);   // returns the thread identifier

                                    // Check the return value for success.
                                    // If CreateThread fails, terminate execution.
                                    // This will automatically clean up threads and memory.
        if (hThreadArray[i] == NULL)
        {
            ExitProcess(3);
        }
    } // End of main thread creation loop.

      // Wait until all threads have terminated.
    WaitForMultipleObjects(MAX_THREADS, hThreadArray, TRUE, INFINITE);

    // Close all thread handles and free memory allocations.
    for (int i = 0; i<MAX_THREADS; i++)
    {
        CloseHandle(hThreadArray[i]);
    }

    return 0;
}

提供输出



这表明初始化静态变量s实际上不是线程安全的。

最佳答案

是的，它确实。测试是错误的。从MyThreadFunction中删除单词sleeper会显示预期的输出

关于c++ - VS2015中的C++局部静态变量初始化线程安全吗，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/40390168/