BUG: Poor Performance With Forms Containing Many Objects

ID: Q197510

The information in this article applies to:

SYMPTOMS

Instantiating a form or container that contains many objects, may be much slower in Visual FoxPro version 6.0 than in Visual FoxPro version 5.0.

If the form contains a pageframe with multiple pages, page activation may be much slower in Visual FoxPro 6.0 than in Visual FoxPro 5.0.

Normally, this behavior does not manifest itself unless the form or container instantiated contains at least several hundred objects.



STATUS

Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article.


MORE INFORMATION

Steps to Reproduce Behavior

  1. Run the following code from a program (.prg) file: 
    
   * This program creates a number of forms that each
   * add a pageframe at run-time. Each page activates
   * after the pageframe is instantiated. The number of forms,
   * pages in the pageframe, and text boxes on each page
   * are set from the #DEFINE statements. The times in seconds for
   * each form to add its objects, and activate each page
   * are echoed to the Debug Output window. The total time in
   * seconds for all forms is echoed last.
      
   #DEFINE NO_OF_FORMS          10
   #DEFINE NO_OF_PAGES          20
   #DEFINE NO_OF_TEXTBOXES      10

   DEBUG
   DEBUGOUT ''

   PUBLIC gnStart
   gnStart = SECONDS()
   FOR lni = 1 TO NO_OF_FORMS
      lcfrmName = 'oform'+ALLTR(STR(lni))
      &lcfrmName = CREATEOBJECT('perfform')
      &lcfrmName..CAPTION = SUBSTR(lcfrmName,2)
      &lcfrmName..SHOW()
   ENDFOR

   FOR lnj = 1 TO _SCREEN.FORMCOUNT
      lcfrmName = 'oform'+ALLTR(STR(lnj))
      &lcfrmName..SHOW()
      lnstart = SECONDS()
      FOR lnk = 1 TO &lcfrmName..pf1.PAGECOUNT
         &lcfrmName..pf1.ACTIVEPAGE = lnk
      ENDFOR
      DEBUGOUT 'Form '+ ALLTR(STR(lnj)) + ;
         ':                 '+alltr(str(SECONDS() - lnstart,5,2))
   ENDFOR
  DEBUGOUT 'All forms:             '+alltr(str(SECONDS() - gnStart,5,2))
   READ EVENTS

    DEFINE CLASS perfform AS FORM
     HEIGHT = 350
     ADD OBJECT pf1 AS PAGEFRAME WITH ;
       PAGECOUNT = 0
     PROC pf1.INIT()
        THIS.HEIGHT = THIS.PARENT.HEIGHT - 5
        FOR lnj = 1 TO NO_OF_PAGES
           THIS.ADDOBJECT('pg'+ALLTR(STR(lnj)), 'pg')
        ENDFOR
     ENDPROC
   ENDDEFINE

   DEFINE CLASS pg AS PAGE
     PROC ACTIVATE()
        IF TYPE('this.cntPage') # 'O'
           THIS.ADDOBJECT("cntPage", "cnPageContainer")
        ENDIF
     ENDPROC
   ENDDEFINE

   DEFINE CLASS cnpagecontainer AS CONTAINER
      NAME = "cnpagecontainer"
      VISIBLE = .T.
      Top = 5
      ADD OBJECT cmd1 AS COMMANDBUTTON WITH ;
         LEFT = 180, ;
         TOP = 20, ;
         CAPTION = 'Quit', ;
         VISIBLE = .T.

      PROC INIT()
         THIS.HEIGHT = THIS.PARENT.PARENT.HEIGHT - 20
         THIS.WIDTH = THIS.PARENT.PARENT.WIDTH - 5
         FOR lnp = 1 TO NO_OF_TEXTBOXES
            THIS.ADDOBJECT('lbl'+ALLTR(STR(lnp)), 'label')
            WITH THIS.CONTROLS(lnp+1)
               .LEFT = 10
               .TOP = 25*(lnp-1)+ 2
               .WIDTH = 80
               .NAME = 'lbl'+ALLTR(STR(lnp))
               .VISIBLE = .T.
            ENDWITH
         ENDFOR
         FOR lnq = lnp TO (2 * lnp) - 2
            THIS.ADDOBJECT('txt'+ALLTR(STR(lnq)), 'textbox')
            WITH THIS.CONTROLS(lnq+1)
               .HEIGHT = 23
               .LEFT = 90
               .TOP = 25*(lnq-lnp)+ 2
               .WIDTH = 80
               .NAME = 'txt'+ALLTR(STR(lnq))
               .VISIBLE = .T.
            ENDWITH
         ENDFOR
      ENDPROC

      PROC cmd1.CLICK
         gnStart = SECONDS()
         CLEAR EVENTS
      ENDPROC
   ENDDEFINE


  2. Note the "All forms:" time in the Debug Output window. This will be around five times higher in Visual FoxPro 6.0 than in Visual FoxPro 5.0.


This example is specifically designed to exhibit the behavior. As written, it instantiates over 2000 objects and activates 200 pages. The impact of this issue on your application is likely to be much less, since most applications do not simultaneously instantiate 200 pages with 10 objects each.

Additional query words: kbVFP6QFE 


Keywords          : kbOOP kbPerfMon kbVFp600bug kbVFP600QFE 
Version           : WINDOWS:6.0
Platform          : WINDOWS 
Issue type        : kbbug

Last Reviewed: July 1, 1999