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I have written an MFC application which uses CRecordset to communicate with MS Access database through ODBC. The problem is with moderate use, the program will appear to pause or hang.. then all database operations will become extremely slow. It is so slow that it is unusable! Is there any reason for this? all help will be appreciated. btw.. my program uses quite a number of recordsets.. e.g to fill comboboxes, update Clistctrls...
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Have a look at its memory usage - Is it increasing and increasing to unreasonable levels? If not RAM is its CPU usage blowing up out of control? If you can give more details such as answers to the above questions you'll get a lot more suggestions.
Steve
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the database operations in the program seem to be allocating awful amounts of memory, in the range of 500 kb for each operation. Is this a sign of a memory leak? also when the program comes to the stage where it is unuseable, the CPU usage doesn't read high. however, the memory usage seems to be quite high (in the range of 30,000 kb).. the program usually uses 14 to 20 mb of memory.
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I don't think that's particularly excessive. If you leave it for an hour and come back how much memory is being used?
Steve
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this problem seems to surface during closing/opening a modeless dialog box repeatedly. The dialog box contains two CListctrls. The problem may lie with the modeless dialog box? Interestingly, other operations not involving creation/destruction of a child window do not cause any problems.
I create the modeless dialog like this:
CQuoteMan* QuoteMan = new CQuoteMan(this);
QuoteMan->Create(IDD_QUOTEMAN,this);
QuoteMan->SetWindowPos( &wndTopMost,100,100, 0, 0, SWP_NOZORDER | SWP_NOSIZE | WS_EX_CONTROLPARENT);
QuoteMan->ShowWindow(SW_SHOW);
and put "delete this" in the destructor of the modeless dialog class.
Also.. this modeless dialog uses 4 separate recordsets. Is there any danger in this?
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You may already be doing this, but how are you closing the child dialogs?
You could try this:
OnClose()
{<br />
DestroyWindow();<br />
delete this;<br />
}
this is this.
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chev_ls1 wrote: Also.. this modeless dialog uses 4 separate recordsets. Is there any danger in this?
Not unless each one is using it's own connection to the datasource. That's one open/close operation times four.
"Let us be thankful for the fools. But for them the rest of us could not succeed." - Mark Twain
"There is no death, only a change of worlds." - Native American Proverb
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Sounds like you eaither A. have a memory leak you could drive a bus through or B. aren't committing database updates.
As a course of action I would have a look at my programs private bytes in performance manager, see if it going up over time. See MSDN "Debugging Techniques" section "Detecting Memory Leaks in MFC" for more information in tracking down your leak.
Otherwise you aren't committing your database changes, are you using transactions ?
Regards
Ray
"Je Suis Mort De Rire"
Blogging @ Keratoconus Watch
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the database operations in the program seem to be allocating awful amounts of memory, in the range of 500 kb for each operation. Is this a sign of a memory leak? also when the program comes to the stage where it is unuseable, the CPU usage doesn't read high. however, the memory usage seems to be quite high (in the range of 30,000 kb).. the program usually uses 14 to 20 mb of memory.
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Hi,
Have you enabled ODBC tracing. It also makes the operations slower.
Bye,
Cool Ju 
Dream Ur Destiny
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what is the diff b/w heapalloc and new .
Pls help me.
never say die
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new uses HeapAlloc internally. But it also adds caching and small block heaps and the like on top of it. new is a C++ keyword where as HeapAlloc is a Win32 API function.
Steve
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Thanks for the answer.
But i want to know is there any thing like private heap and Global heap?
Pls help me
never say die
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No. Win32 supports multiple heaps, you can create your own by calling HeapCreate and keep it to yourself - I guess in that case you could consider it private. Can you explain what you’re trying to do specifically? Maybe then I can be of more help.
Steve
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Actually a project has been given to me which connects the client to IIS Server via soap.I have been assigned to devlope further.So any memory allocation done on Server Side using Heapalloc. When I asked the reason ,i was told that memory is bound(within) to the process so it has been done using HeapAlloc.
If u can help me further,I would be thankful to u
never say die
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Calling new in C++ gets its memory from HeapAlloc underneath the hood. But it integrates with the language by:
- Knowing the size of the object it’s allocating (so you don't have to supply it).
- Calls constructors (and delete calls destructors).
- Avoids casts.
In short I'd just use new and delete. But beware:
If you allocate with new you must free with delete and if you allocate with HeapAlloc you must free it with HeapFree - You can't allocate some memory with new and free the same memory with HeapFree for example.
Steve
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That means if a memory allocation requires construtor for intialization then use new rather than HeapAlloc
never say die
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You could use the a placment new but that's rather advanced.
Steve
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Thanx a lot
never say die
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i don't find HeapAlloc()[^] that similar to new operator...
why not using the language operator, so that it will always work regardless of the plateform ?!
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hi all
i made drawing on dialog through code.
CClientDC dc(this);
dc.moveto();
dc.lineto(); functions
"drawings is complete on dialog now i want that this drawing should be saved on the bitmap file or jpeg file"
for that purpose i m using the code.
CImage Image;
Image.Attach(hBitmap);
Image.Save("D:\\test.bmp");
Image.Detach();
but it require the hBitmap. tell me how to get the hbitmap use the mempry device context to save the the bimtap in memory and then use it or what.
i had tried this code.
CBitmap bmp;
bmp.CreateCompatibleBitmap(dc,400,275);
but no way to get the hbitmap
then i use this code
HDC hdc= CreateCompatibleDC(GetDC()->m_hDC);
HBITMAP hBitmap=CreateCompatibleBitmap(GetDC()->m_hDC,200,200);
SelectObject(hdc,hBitmap);
hBitmap=(HBITMAP)SelectObject(hdc,hBitmap);
and then used it inthe cimage member but it gives empty black bitmap.
ddd
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Hi,
try this
HDC hdc = ::GetDC(hWnd);
CDC dc, memDC;
dc.Attach(hdc);
memDC.CreateCompatibleDC(&dc);
CRect rc;
::GetClientRect(hWnd, &rc);
CSize sz(rc.Width(), rc.Height());
CBitmap bm;
bm.CreateCompatibleBitmap(&dc, sz.cx, sz.cy);
CBitmap *pOldbm = memDC.SelectObject(&bm);
memDC.BitBlt(0, 0, sz.cx, sz.cy, &dc, 0, 0, SRCCOPY);
// now you can do what you need to with bm.m_hObject
memDC.SelectObject(pOldbm);
bm.Detach();
::ReleaseDC(dc.Detach());
Bye,
Cool Ju
Dream Ur Destiny
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HDC hdc = ::GetDC(hWnd);
this line gives error i thinks u had not get mey question i only needed the
HBITMAP variable with ptr to only the drawings not whole window.
ddd
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Hi,
check this link
this[^]
Bye,
Cool Ju
Dream Ur Destiny
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thanks for ur reply
there was only problem with my code was the HBITMAP object was not proerly initilzed i mean there was not value in it now i got the pt where i was wrong
once agin thanks.
ddd
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