来自不同线程的同步输出流

我正在编写一个将写入XML文件的应用程序中的一些数据。我尝试使用事件核心对象对其进行同步，但是在文件中，我得了错误的数据。我得到下一个结果

<file path="somePath" />
<file path="somePath" <file path="somePath" /> />....

，但我希望能得到

<file path="somePath" />
<file path="somePath" />
<file path="somePath" />

请参见下面的伪代码。有什么问题？

unsigned int WINAPI MyThread(void *p)
{
    std::wofstream outstr;
    outstr.open("indexingtest.xml", std::ios::app);
    do
    {
        if(somePredicat1)
        {
            WaitForSingleObject(hEvent, INFINITE);
            outstr <<"<file path=""<< sFileName << ""n";
            outstr <<"tsize=""<< fileSize << "" />n";           
            ReleaseMutex(hMutex);
        }
         if(somePredicat3)
         {
             MyThread(sFileName);
         }
    }while(somePredicat2);
    outstr.close();
    FindClose( hSearch );
    return 0;
}
int _tmain(int argc, TCHAR *argv[])
{
    hEvent = CreateEvent(NULL, TRUE, FALSE, NULL);
    //hMutex = CreateMutex(NULL, FALSE, 0);
    unsigned int ThreadID;
    HANDLE hThread1 = (HANDLE)_beginthreadex(NULL, 0, MyThread, L"D:\*", 0, &ThreadID);
    HANDLE hThread2 = (HANDLE)_beginthreadex(NULL, 0, MyThread, L"C:\*", 0, &ThreadID);
    SetEvent(hEvent);
    std::wcout << "a" << std::endl;
    WaitForSingleObject( hThread1, INFINITE );
    return 0;
}

更多具体代码

HANDLE hMutex = CreateMutex(NULL,FALSE, 0);
wchar_t** GetAllFilesImpl( wchar_t const* folder, wchar_t** res, size_t* pAllocated, size_t* pUsed )
{
    HANDLE hSearch;
    WIN32_FIND_DATAW fileinfo;
    size_t allocatedMemory = 0;

    hSearch = FindFirstFileW( folder, &fileinfo );
    if( hSearch != INVALID_HANDLE_VALUE ) {
        do {
            wchar_t* sFileName, ** tmp, sTmp[ 1024 ];
            long fileSize = 0;
            long creationDate;
            /* ignore ., .. */
            if( !wcscmp(fileinfo.cFileName, L".") ||
                !wcscmp(fileinfo.cFileName, L"..") )
                continue;
            sFileName = PathCreator( folder, fileinfo.cFileName );
            fileSize = fileinfo.nFileSizeLow;
            creationDate = fileinfo.ftCreationTime.dwHighDateTime;

            if(fileSize)
            {
                WaitForSingleObject(hMutex, INFINITE);
                std::wofstream outstr;
                            outstr.open("indexingtest.xml", std::ios::app);
                outstr.seekp(std::ios_base::end);
                outstr <<"<file path=""<< sFileName << ""n";
                outstr <<"tsize=""<< fileSize << "" />n";
                outstr.seekp(std::ios_base::end);
                outstr.close();
                wprintf( L"%sn", sFileName);
                ReleaseMutex(hMutex);
            }
            tmp = AddToArray( res, pAllocated, pUsed, sFileName );
            if( !tmp ) return FreeAllFilesMemory(res), NULL;
            res = tmp;
            if( fileinfo.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY ) {
                wcscpy_s( sTmp, sFileName );
                wcscat_s( sTmp, L"\*" );
                tmp = GetAllFilesImpl( sTmp, res, pAllocated, pUsed );
                if( !tmp ) return NULL;
                res = tmp;
            }
        } while( FindNextFileW(hSearch, &fileinfo) );
        FindClose( hSearch );
    }
    return res;
}
unsigned int WINAPI GetAllFiles( void* folder )
{
    size_t nAllocated = 0, nUsed = 0;
    wchar_t** res = GetAllFilesImpl( (wchar_t *)folder, NULL, &nAllocated, &nUsed );
    if( res ) {
        /* to indicate end of result add a NULL string */
        wchar_t** tmp = AddToArray( res, &nAllocated, &nUsed, NULL );
        if( !tmp ) return FreeAllFilesMemory(res), -1;
        res = tmp;
    }
    std::wcout << "a" << std::endl;
    return 0;
}
int _tmain(int argc, TCHAR *argv[])
{
    Sleep(1000);
    unsigned int ThreadID;
    HANDLE hThreads[3];
    hThreads[0] = (HANDLE)_beginthreadex(NULL, 0, GetAllFiles, L"D:\*", 0, &ThreadID);
    hThreads[1] = (HANDLE)_beginthreadex(NULL, 0, GetAllFiles, L"C:\Users\Andrew\Desktop\*", 0, &ThreadID);
    hThreads[2] = (HANDLE)_beginthreadex(NULL, 0, GetAllFiles, L"E:\*", 0, &ThreadID);
    unsigned int dw = WaitForMultipleObjects(3, hThreads, TRUE, INFINITE);
    CloseHandle(hFile);
    printf("finishedn");
    return 0;
}