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Q193724: PRB: Memory Leak Passing Arrays from VBScript to VFP

Article: Q193724
Product(s): Microsoft FoxPro
Version(s): WINDOWS:6.0
Operating System(s): 
Keyword(s): kbGrpDSFox
Last Modified: 01-JUL-1999

-------------------------------------------------------------------------------
The information in this article applies to:

- Microsoft Visual FoxPro for Windows, version 6.0 
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SYMPTOMS
========

When passing an array from VBScript code to a Visual FoxPro Component Object
Model (COM) Server, memory usage increases.

CAUSE
=====

For every STRING or UNITIALIZED array element, you lose one handle and 8 bytes
of memory.

RESOLUTION
==========

The following workaround initializes all elements of the array with numeric data
or Null before sending it to the COM Server.

  <%@ LANGUAGE=VBScript ENABLESESSIONSTATE=False %>
  <html>
  <body>
  <p><b>This is a test</b></p>

  <%
  dim myarray(30)
  for i = 0 to 29
     myarray(i) = 0 'Or Null
  next

  set ox = Server.CreateObject("arrayhandler.arrayhandler")
  response.write ox.myeval("'<br>'+vers(1)+'</br><br> '+time()+" + _
  "' </br>'")
  response.write  ox.myeval("'<br>UserMem:'+sys(1016) + '</br>'")

  ox.DoNothingToArray myarray

  set myarray(2) = NOTHING
  set myarray(0) = NOTHING
  set myarray(1) = NOTHING

  set ox = NOTHING
  set zzz = NOTHING

  %>
  </body>
  </html>

STATUS
======

Microsoft is researching this problem and will post new information here in the
Microsoft Knowledge Base as it becomes available.

MORE INFORMATION
================

Steps to Reproduce Behavior
---------------------------

1. In a project named ArrayHandler, add the following code to the Main program:

  DEFINE CLASS arrayhandler AS CUSTOM OLEPUBLIC
    PROCEDURE DoNothingToArray
       PARAM myarray
       EXTERNAL ARRAY myarray
       RETURN
    ENDPROC
    PROC mydocmd(p1)
        &p1
    PROC myeval(p1)
        RETURN EVAL(p1)
  ENDDEFINE

2. Build that project into a COM .dll file named ArrayHandler.dll.

3. Use the following code in an Active Server Page called ArrayTest.asp:

  <%@ LANGUAGE=VBScript ENABLESESSIONSTATE=False %>
  <html>
  <body>
  <%
  dim myarray(30)
  myarray(0) = "blah"

  set ox = Server.CreateObject("arrayhandler.arrayhandler")
  response.write ox.myeval("'<br>'+vers(1)+'</br><br> '+"+ _
  "time() + ' </br>'")
  response.write  ox.myeval("'<br>UserMem:'+sys(1016) + '</br>'")

  ox.DoNothingToArray myarray

  set myarray(2) = NOTHING
  set myarray(0) = NOTHING
  set myarray(1) = NOTHING

  set ox = NOTHING
  set zzz = NOTHING

  %>
  </body>
  </html>

4. Place the ArrayHandler.dll on a computer that has Internet Information Server
  (IIS) and register the COM server.

5. Place the Active Server Page created in Step 3 in the InetPub\WWWRoot
  directory on the IIS Server.

6. Run the .asp page by typing the following in the Address line of Internet
  Explorer on the IIS Server and then press ENTER:
  http://LOCALHOST/ARRAYTEST.ASP

When the page displays, press the F5 key to refresh. Notice the memory increase
with each refresh.

Additional query words: kbVFp600 kbCOMt kbISAPI kbInternet kbVBScript

======================================================================
Keywords          : kbGrpDSFox 
Technology        : kbVFPsearch kbAudDeveloper kbVFP600
Version           : WINDOWS:6.0
Issue type        : kbprb
Solution Type     : kbpending

=============================================================================

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