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

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

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

Keywords : kbole kbVFp FxprgGeneral
Version : WINDOWS:5.0,5.0a
Platform : WINDOWS
Issue type : kbbug