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Q176777: FIX: Multi-Use OLE .Exe File Not Releasing Memory

Article: Q176777
Product(s): Microsoft FoxPro
Version(s): WINDOWS:5.0,5.0a
Operating System(s): 
Keyword(s): kbole kbvfp
Last Modified: 18-JUN-1999

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The information in this article applies to:

- Microsoft Visual FoxPro for Windows, versions 5.0, 5.0a 
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SYMPTOMS
========

When you use a multi-use OLE out-of-process server (.exe), memory is not
released in the process until all of the objects have been released.

RESOLUTION
==========

When an OLE .exe file is going to be used for long periods of time without the
release of the last object you can use the following workaround:

1. Build two OLE .exe files with different GUIDs and place them on the computer.
  NOTE: To generate a different GUID for the second instance of the OLE .exe,
  select the "Regenerate OLE Server Ids" option when you build the Visual
  FoxPro project.

2. In the client, have a procedure that runs before instantiating the object
  that checks the current system date and time.

3. When you switch from one server to the other, you release all instances of
  the OLE server you are switching from. Perform this switch at regular
  increments to minimize the effect of the OLE server holding the memory.

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 FoxPro 6.0.

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

In a multi-use out-of-process OLE server, memory usage increases with each
additional instantiation of an object or class in the server. When you release
these class instantiations, memory usage does not decrease until the last object
is released. Memory then decreases incrementally and the .exe file unloads from
memory.

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

1. Create and build an out-of-process (.exe) multi-use OLE server in Microsoft
  Visual FoxPro.

  NOTE: To create a Multi-Use OLE server, click the Servers tab in the Project
  Information dialog box and select Multi Use for the Instance option.

2. In Microsoft Visual FoxPro create an instance of the OLE server.

3. Using a tool like Microsoft Windows NT Task Manager, view the memory usage
  for the OLE .exe file. In Microsoft Windows NT, this is located on the
  Processes tab of the Task Manager.

4. Create additional instances of the object and note the increased memory usage
  of the OLE .exe file.

5. Release instances of the object one by one and note that the memory usage
  does not decrease.

6. Release the last instance of the OLE server. Notice the memory decreases and
  the .exe file exits from the Processes list.

Additional query words: COM DCOM

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Keywords          : kbole kbvfp 
Technology        : kbVFPsearch kbAudDeveloper kbVFP500 kbVFP500a
Version           : WINDOWS:5.0,5.0a
Issue type        : kbbug
Solution Type     : kbfix

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