Memory leaks in MFC while using CDatabase::OpenEx()

Question

Hi,
This question has been asked previously but the explanation was not in detail and i could never reach to the bottom of it.
I hope i can elaborate more on the problem statement and i can get a resolution/explanation from the experts here.
Consider the following two sample codes;
1.
int count = 200;
for (int i=0; i <count; ++i)
try
CDatabase *db = new CDatabase;
BOOL bRes = db->OpenEx(_T("DSN=MyData;UID=anon;PWD=pass"));
db->Close();
delete db;
db=NULL;
catch (CDBException* e)
e->Delete();
2.
CDatabase *db = new CDatabase;
int count = 200;
for (int i=0; i <count; ++i)
try
BOOL bRes = db->OpenEx(_T("DSN=MyData;UID=anon;PWD=pass"));
db->Close();
catch (CDBException* e)
e->Delete();
delete db;
db=NULL;
return 0;
delete db;
db=NULL;
The first sample code leaks a lot of memory and it can be easily observed from the task manager, the memory usage keeps on growing.
The second sample code does not leak any memory if i observe the memory usage from the task manager.
To find out the cause of the memory leak i ran the code through rational purify, both the codes are leaking memory according to rational purify. The first code leaks significantly more memory than the second one. The DLL pointed by rational purify are MFC
DLLs (inserting the screen shot below)
Is this a known issue with the MFC DLL or am i doing something wrong?
I have a server application where i have to create CDatabase object multiple times and i end up leaking a lot of memory over a period of time.
I can provide more information about this issue if required. Thanks in advance.

Answer 1

I am trying to reproduce this issue on my side, but it seem there is no memory leak in my simple sample. I use _CrtDumpMemoryLeaks() to test the memory leak.
https://msdn.microsoft.com/en-us/library/d41t22sb.aspx
If I comment this line: db->Close();
I can detect the memory leak at CDatabase
*db =
new CDatabase; 
See the screenshot.
If follow your sample code, there is memory leak message in the output view pane.
#define CRTDBG_MAP_ALLOC
#include <stdlib.h>
#include <crtdbg.h>
#ifdef _DEBUG
#define new DEBUG_NEW
#endif.....int CMFCCdbMLTestApp::ExitInstance()
// TODO: Add your specialized code here and/or call the base class
_CrtDumpMemoryLeaks();
return CWinApp::ExitInstance();
May you can use some use tool like WinDbg tool to find more information about this issue. 
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