Question

由于遗留原因，我的应用程序使用MS Access mdb文件。它使用ADO连接到数据库，并带有以下连接字符串：

Provider = Microsoft.Jet.OLEDB.4.0; Persist Security Info = False; Data Source = Dummy.mdb

最近我开始将我的应用程序移植到64位。由于Jet OLEDB提供程序在64位系统上不可用，我使用了ACE OLEDB提供程序，其中包含以下连接字符串：

Provider = Microsoft.ACE.OLEDB.12.0; Persist Security Info = False; Data Source = Dummy.mdb

该应用程序还使用MS XML DOM来处理XML文件。有时64位版本在SysFreeString中发生访问冲突异常崩溃，该异常是从一个MS XML包装器方法调用的。 32位版本没有这些问题。我将问题提炼到测试人员应用程序中。

#define _WIN32_WINNT 0x0501

#include <stdio.h>
#include <windows.h>
#include <process.h>
#include <conio.h>
#include <ObjBase.h>

#import <msxml6.dll>
#import <msado15.dll> rename("EOF", "EndOfFile")

using namespace ADODB;

bool s_bRepeat = true;

unsigned __stdcall XmlThreadFunc(void*)
{
  CoInitializeEx(NULL, COINIT_APARTMENTTHREADED);
  MSXML2::IXMLDOMDocumentPtr l_pXMLDom;
  l_pXMLDom.CreateInstance(__uuidof(DOMDocument), NULL, CLSCTX_INPROC_SERVER);
  l_pXMLDom->async = VARIANT_FALSE;
  MSXML2::IXMLDOMElementPtr l_pRoot = l_pXMLDom->createElement("root");
  l_pXMLDom->appendChild(l_pRoot);
  unsigned int l_nCnt = 0;
  while (s_bRepeat)
  {
    if (0 == l_nCnt++ % 1000)
    {
      printf(".");
    }
    l_pRoot->setAttribute("test", "Test1");
    Sleep(0);
  }
  CoUninitialize();
  _endthreadex(0);
  return 0;
} 

unsigned __stdcall DbThreadFunc(void*)
{
  CoInitializeEx(NULL, COINIT_APARTMENTTHREADED);
  _ConnectionPtr l_pConnection;
  l_pConnection.CreateInstance(__uuidof(Connection));
#ifdef _WIN64
  LPCSTR l_cszConnectStr = "Provider=Microsoft.ACE.OLEDB.12.0;Persist Security Info=False;Data Source=Dummy.mdb";
#else
  LPCSTR l_cszConnectStr = "Provider=Microsoft.Jet.OLEDB.4.0;Persist Security Info=False;Data Source=Dummy.mdb";
#endif
  while (s_bRepeat)
  {
    l_pConnection->Open(l_cszConnectStr, "", "", adConnectUnspecified);
    Sleep(1000);
    printf("(");
    l_pConnection->Close();
    printf(")");
  }
  CoUninitialize();
  _endthreadex(0);
  return 0;
} 

int main()
{
  HANDLE l_hXmlThread = reinterpret_cast<HANDLE>(_beginthreadex(NULL, 0, &XmlThreadFunc, NULL, 0, NULL));
  HANDLE l_hDbThread = reinterpret_cast<HANDLE>(_beginthreadex(NULL, 0, &DbThreadFunc, NULL, 0, NULL));
  _getch();
  s_bRepeat = false;
  HANDLE l_Handles[2] = { l_hXmlThread, l_hDbThread };
  WaitForMultipleObjects(2, l_Handles, TRUE, INFINITE);
  CloseHandle(l_hXmlThread);
  CloseHandle(l_hDbThread);
  return 0;
}

崩溃调用堆栈如下：

OLEAUT32!SysFreeString
TestCrash64Lean!_bstr_t::Data_t::_Free
TestCrash64Lean!_bstr_t::Data_t::~Data_t
TestCrash64Lean!_bstr_t::Data_t::`scalar deleting destructor'
TestCrash64Lean!_bstr_t::Data_t::Release
TestCrash64Lean!_bstr_t::_Free
TestCrash64Lean!_bstr_t::~_bstr_t
TestCrash64Lean!MSXML2::IXMLDOMElement::setAttribute
TestCrash64Lean!XmlThreadFunc
MSVCR80D!_callthreadstartex
MSVCR80D!_threadstartex
kernel32!BaseThreadInitThunk
ntdll!RtlUserThreadStart

崩溃时，DB线程始终处于以下状态：

MSVCR90!memset
mso!Ordinal4118
mso!Ordinal7994
mso!MsoUninitOffice
ACECORE
ACECORE
ACEOLEDB!DllGetClassObject
ACEOLEDB!DllGetClassObject
ACEOLEDB!DllGetClassObject
ACEOLEDB!DllGetClassObject
oledb32!CAcm::FinalRelease
oledb32!ATL::CComPolyObject<CDCM>::~CComPolyObject<CDCM>
oledb32!ATL::CComPolyObject<CDCM>::Release
oledb32!CDCMCreator::DestroyResource
comsvcs!CHolder::SafeDispenserDriver::DestroyResource
comsvcs!CHolder::ProcessDestroyList
comsvcs!CHolder::FreeResource
oledb32!CDCMCreator::ReleaseResource
oledb32!CDPO::ReturnDCMToPool
oledb32!CDPO::FinalRelease
oledb32!ATL::CComPolyObject<CDPO>::`scalar deleting destructor'
oledb32!ATL::CComPolyObject<CDPO>::Release
msado15!CConnection::_Close
msado15!CConnection::Close
TestCrash64Lean!ADODB::Connection15::Close
TestCrash64Lean!DbThreadFunc
MSVCR80D!_callthreadstartex
MSVCR80D!_threadstartex
kernel32!BaseThreadInitThunk
ntdll!RtlUserThreadStart

我发现作为一种解决方法，如果我保持与一些空数据库文件的一个开放连接，我可以打开和关闭与实际数据库文件的连接，并且应用程序不会崩溃。无论如何，我宁愿了解坠机的实际原因。我很感激任何建议。

我的配置如下：

Microsoft Visual Studio 2005版本8.0.50727.4039（QFE.050727-4000）
  Windows Server 2008 R2标准版64位
  处理器：Intel（R）Xeon（R）E5645 @ 2.40GHz
  内存：16.0 GB

Answer 1

看起来这是来自Microsoft Access数据库引擎2010可再发行组件的ACE OLEDB提供程序的问题。从Microsoft Access 2013 Runtime切换到提供程序解决了该问题。

64位ACE OLEDB提供程序导致SysFreeString中的访问冲突

1 个答案: