FIX: Cached Class Factorys Get Released by Illegal Thread

ID: Q171549

The information in this article applies to:

Microsoft Visual Basic Professional and Enterprise Editions for Windows, version 5.0
Microsoft Visual Studio 97

SYMPTOMS

Cached Class Factorys can get released by illegal thread.

CAUSE

The repository maintains a cache of class factorys. If a class factory has not been accessed for a short period of time, the reference to the class factory will get released. However, the reference is released from a different thread than the one that initially obtained the reference.

STATUS

Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article. This bug has been fixed in Visual Studio 97 Service Pack 3.

For more information, please see the following article in the Microsoft Knowledge Base:

   ARTICLE-ID: Q170365
   TITLE     : INFO: Visual Studio 97 Service Packs - What, Where, and Why

For a list of the Visual Basic 5.0 bugs that were fixed in the Visual Studio 97 Service Pack 3, please see the following article in the Microsoft Knowledge Base:

   ARTICLE-ID: Q175450
   TITLE     : INFO: Visual Basic 5.0 Fixes in Visual Studio 97
               Service Pack 3

MORE INFORMATION

The behavior above violates the apartment-threading model, and can cause a crash.

This behavior is evident when a repository object is implemented in Visual Basic. This only occurs in Visual Basic where a class is defined as the class that is the implementation of the generic repository class. This behavior occurs when the ClassID for the Visual Basic class matches the repository classdef's ClassID. It crashes when the client creates an instance before the cache is released. When the engine releases the class factory cache, the crash occurs.

Keywords          : kbVBp500 kbVS97sp2fix kbvbp500sp3fix 
Version           : WINDOWS:5.0; WINNT:97
Platform          : WINDOWS winnt
Issue type        : kbbug
Solution Type     : kbfix

Last Reviewed: December 3, 1997