Q294888: BUG: Instantiation of ActiveX EXE SingleUse Objects Is Blocked

Article: Q294888
Product(s): Microsoft Visual Basic for Windows
Version(s): 6.0
Operating System(s): 
Keyword(s): kbActiveX kbClient KbClientServer kbCOMt kbLocalSvr kbOSWin2000 kbVBp600 kbGrpDSVB kbDS
Last Modified: 15-AUG-2002

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

- Microsoft Visual Basic Enterprise Edition for Windows, version 6.0, used with:
   - the operating system: Microsoft Windows 2000 
-------------------------------------------------------------------------------

SYMPTOMS
========

If a client instantiates an object from a SingleUse class in an ActiveX EXE
server, and another client tries to instantiate the same SingleUse class while
the first instance is processing messages (for example, while the first instance
is running some code), the second client is blocked. Thus, the second instance
of the ActiveX EXE is not started until the first instance has finished
processing.

This blocking occurs only in environments that are running Windows 2000 and
Windows 2000 Service Pack 1 (SP1). Blocking does not occur on Windows NT 4.0 (in
any of its service packs).

RESOLUTION
==========

To resolve this problem, obtain the latest service pack for Windows 2000. For
additional information, click the following article number to view the article
in the Microsoft Knowledge Base:

  Q260910 How to Obtain the Latest Windows 2000 Service Pack


Another resolution to this issue is found in the following Microsoft Knowledge
Base article:

  Q313582 INFO: Availability of Windows 2000 Post-Service Pack 2 COM+ Hotfix
  Rollup Package 18.1

STATUS
======

Microsoft has confirmed that this is a problem in Microsoft Windows 2000. This
problem was first corrected in Windows 2000 Service Pack 2.

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

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

Create the Server:

1. Create a new ActiveX EXE project in Visual Basic. Class1 is created by
  default.

2. From the Properties window, change the Instancing property of Class1 to
  SingleUse.

3. Rename Class1 as "clsServer" (without the quotation marks).

4. Rename the project "proServer" (without the quotation marks).

5. Add the following code to clsServer:

  Private Declare Sub Sleep Lib "kernel32" (ByVal dwMilliseconds As Long)

  Public Sub DoSomething(x As Long)
      Sleep (x)
  End Sub

6. Save the project. From the File menu, click "Make proServer.exe" to compile
  the project.

Create the Client:

1. Create a new Standard EXE project in Visual Basic. Form1 is created by
  default.

2. From the Project menu, click References, select the proServer.exe check box,
  and then click OK.

3. Add a CommandButton control to Form1.

4. Add the following code to Form1:

  Private obj As proServer.clsServer

  Private Sub Command1_Click()
      Set obj = New proServer.clsServer
      obj.DoSomething (100000)
  End Sub

5. Save the project. From the File menu, click "Make project1.exe" to compile
  the client.

Reproduce the Blocking Behavior:

1. On a Windows 2000-based computer, run two instances of the client EXE.

2. On the first client instance, click Command1 to start proServer.exe.

3. On the second client instance, click Command1. Notice that no new instance of
  proServer.exe is started until the first instance has finished processing the
  DoSomething call.

Additional query words: kbIISCom launch

======================================================================
Keywords          : kbActiveX kbClient KbClientServer kbCOMt kbLocalSvr kbOSWin2000 kbVBp600 kbGrpDSVB kbDSupport kbCOMIS kbWin2000SP2Fix kbgrpdsvc kbWin2000sp3fix 
Technology        : kbVBSearch kbAudDeveloper kbZNotKeyword6 kbZNotKeyword2
Version           : :6.0
Issue type        : kbbug
Solution Type     : kbfix

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

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY.

Copyright Microsoft Corporation 1986-2002.