Why CreateNewFrame() returns as NULL after successful created 136 child frame window and trying to create 137th child frame window in MDI application

Question

I am working on MDI application which was developed in VC++ in VS 2012. When my application is launched, it will display a Tree. Under a tree there are 254 nodes. Basically
these nodes data are read from Configuration xml file and loaded into the Tree. By double clicking on each node, first it will create object for document class ( By calling CreateNewDocument() method) after that member variables for that
document class will be initialized and then it will create the new frame window (by calling
CreateNewFrame(pDoc,NULL). New child frame window will show under Main window to the user.
User able to see the data from child frame window.
Similarly by double clicking on each node it will create another object for the same document class and new child frame window will be opened for that node. Each child frame window runs
in different data and showed under the Main window.
Existing requirement by double clicking on each node, node data shall show in separate child window and there is no requirement for all 254 child windows opened simultaneously.
But current requirement is , all 254 child windows shall open simultaneously by double clicking on each node one by one.
In debug mode I have tried double clicking on each node. I able to open up to 50 nodes. After 50th child windows are opened, I unable to access to the application
(Unable to open further node data window since application is getting hanged).
Each child window is having tree, multiple splitter window and some additional controls (static text, ...).
Same I have tried in release mode, I able to open up to 136 child windows. After that the application fail to create the new frame window in VS 2012. i.e CreateNewFrame() return
NULL after successful created 136 child frame window. Debug purpose I have added the code to retrieve last error code by calling GetLastError() method. I got the value as "0". By closing any existing child window then I able to open remaining nodes.
At any point of time I can reach maximum of 136 child frame window that can be opened under Main window. Failing to open all 254 child frame window
simultaneously,  currently I fail to meet the current requirement.
current Requirement is all 254 child frame window are opened simultaneously. Please let me know what may be the reason fail to create new frame window after 136 frame window that are
opened already. In Microsoft site, mentioned that there is no limitation for creating frame  window in MDI application. I have tried another sample MDI application having limited number of controls, in which I able to create "n"
number of child frame windows. why not able to create more than 136 child frame window in my actual application?
Is there any possibility by changing project settings allow me to create 254 child frame window??
Code Snippet as below:
CDiagBaseDoc * CDiagBaseMDocTemplate::OpenDiagView( ...)
     CDiagBaseDoc* pDoc = NULL;
    if (pDoc == NULL)
        pDoc = (CDiagBaseDoc*)CreateNewDocument();
    if ( pDoc )
       CFrameWnd* pFrame = NULL;
       if (bAlreadyOpen)
              // If Child frame window already opened, then handling the code here.
     else
           pFrame = CreateNewFrame(pDoc, NULL);
           if (pFrame == NULL)
              ASSERT(FALSE);
              delete pDoc;       // explicit delete on error
             pDoc = NULL;
          ASSERT_VALID(pFrame);
          if( pDoc != NULL ) //VS2012
             if ( !pDoc->OnNewDocument() )
                TRACE0("CDocument::OnNewDocument returned FALSE\n");
                delete pDoc;       // explicit delete on error
                pDoc = NULL;
                pFrame->DestroyWindow();
                 pFrame = NULL;
       if (pFrame)
           InitialUpdateFrame(pFrame, pDoc);
           ShowWindow( pFrame->GetSafeHwnd(), SW_MAXIMIZE ); //when opening node for the 1st time, maximize it
}<o:p></o:p>

Answer 1

Hi MuruganK,
Have you checked how much memory your application used? You could check it by Task Manager. Maybe your application reach Memory Limits for Windows.
https://msdn.microsoft.com/en-us/library/windows/desktop/aa366778%28v=vs.85%29.aspx?f=255&MSPPError=-2147217396
Is it possible that there are some memory leaks in your application? It would better if you have made a simple sample to reproduce and narrow down this issue.
Best regards,
Shu
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