FIX: Return of COM Server Objref Causes Server to Not Release

• Microsoft Visual FoxPro for Windows, versions 5.0, 5.0a, 6.0

SYMPTOMS

You have an application that instantiates a COM server object and stores a reference to it in a variable. The COM object instantiates a second COM server object and returns an object reference to it. Even if the variable containing the reference to the first COM server is released, the first COM server remains in memory until the second COM server is released.

STATUS

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

This bug was corrected in Visual Studio 6.0 Service Pack 3.

For more information about Visual Studio service packs, please see the following articles in the Microsoft Knowledge Base:

Q194022 INFO: Visual Studio 6.0 Service Packs, What, Where, Why

Q194295 HOWTO: Tell That Visual Studio 6.0 Service Packs Are Installed

MORE INFORMATION

Steps to Reproduce Behavior

1. Make sure that no instances of Excel are running, and only a single instance of Visual FoxPro is running.



2. Run the following code from a program (.PRG) file:




#DEFINE CR_LF CHR(13)+CHR(10)
CLEAR ALL
LOCAL oVFP, oExcel
* Create VFP as a COM server
oVFP=CREATEOBJECT("visualfoxpro.application")

* Tell the server to create Excel as COM server, and return it
oExcel = oVFP.EVAL("createobject('excel.application')")
?oExcel.NAME		&& Returns Excel

=MESSAGEBOX('Check the task manager or task list.'+ CR_LF + CR_LF + ;
   'You will see 2 instances of VFP and 1 of Excel.'+ CR_LF + ;
   'Press OK to proceed.',16, 'MessageBox 1')

* Release VFP server reference
oVFP = NULL
=MESSAGEBOX('Check the task manager or task list.'+ CR_LF + CR_LF + ;
   'You will STILL see 2 instances of VFP and 1 of Excel.'+ CR_LF + ;
   'Press OK to proceed.', 16, 'MessageBox 2')

* The following releases all servers OK
CLEAR ALL 

3. When MessageBox 1 is displayed, look at the list of running programs in the Windows NT Task Manager or the Windows 9x task list. You will see two instances of Visual FoxPro and one instance of Excel. This is as expected.



4. Click OK in MessageBox 1.



5. When MessageBox 2 is displayed, again look at the list of running programs in the Windows NT Task Manager or the Windows 9x task list. You will still see two instances of Visual FoxPro and one instance of Excel. One of the instances of Visual FoxPro should have been released.

© Microsoft Corporation 1999, All Rights Reserved.
Contributions by Jim Saunders, Microsoft Corporation

Additional query words:

Keywords : kbCOMt kbVFp500abug kbVFp600 kbVFp600bug kbVS600sp3fix kbGrpFox kbDSupport
Version : WINDOWS:5.0,5.0a,6.0
Platform : WINDOWS
Issue type : kbbug