DOCUMENT:Q171549  01-DEC-1997  [vbwin]
TITLE   :FIX: Cached Class Factorys Get Released by Illegal Thread
PRODUCT :Microsoft Visual Basic for Windows
PROD/VER:WINDOWS:5.0; WINNT:97
OPER/SYS:WINDOWS winnt
KEYWORDS:vb5all VS97FixlistSP3 VB5FixListSP3

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

 - Microsoft Visual Basic Professional and Enterprise Editions for
   Windows, version 5.0
 - Microsoft Visual Studio 97
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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          : vb5all VS97FixlistSP3 VB5FixListSP3
Version           : WINDOWS:5.0; WINNT:97
Platform          : WINDOWS winnt
Issue type        : kbbug
Solution Type     : kbfix kbservicepack

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

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Copyright Microsoft Corporation 1997.