KnowledgeBase Archive

An Archive of Early Microsoft KnowledgeBase Articles

View on GitHub

Q159350: SNA Server Win32 API Calls May Not Return to Multithreaded App

Article: Q159350
Product(s): Microsoft SNA Server
Version(s): WINDOWS:2.0,2.1,2.11,2.11 SP1,2.11 SP2,3.0,3.0 SP1,3.0 SP2,3.0 SP3,4.0,4.0 SP1,4.0 SP2
Operating System(s): 
Keyword(s): kbnetwork kbprogramming
Last Modified: 12-JUN-2001

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

- Microsoft SNA Server, versions 2.0, 2.1, 2.11, 2.11 SP1, 2.11 SP2, 3.0, 3.0 SP1, 3.0 SP2, 3.0 SP3, 4.0, 4.0 SP1, 4.0 SP2 
-------------------------------------------------------------------------------

SYMPTOMS
========

If you write a multithreaded 32-bit Windows application to handle multiple
concurrent CPIC conversations, you may find that some of the application's
threads hang, for example on a CPIC request (CMALLC or CMRCV); these threads
never complete. The problem occurs when up to 90 concurrent threads (each one
handling a different CPIC conversation) are spawned.

CAUSE
=====

The problem is caused by the application. The application calls the
_beginthread() function to create a new thread, and then closes this thread
handle from the main application as soon as _beginthread() completed
successfully.

WORKAROUND
==========

To work around this problem:

1. Remove the close request from the application.

2. Terminate each thread by calling the _endthread function.

Also see the reference section below for information on a better way to write
such applications.

The problem was solved when this close request was removed from his application.
Each thread was terminated by calling the _endthread function.

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

This problem could occur with any 32-bit Windows application that uses threads
in this manner, when using the SNA Server API's (APPC, CPIC, and LUA RUI or
SLI), or even Windows sockets.

See the following Microsoft Knowledge Base article in the visualc database for
information on using the _beginthreadex() and _endthreadex() functions:

  Q132078 How to Use _beginthreadex() and _endthreadex()

These functions ( _beginthreadex() and _endthreadex() ) are recommended instead
of the _beginthread() and _endthread() functions, which can lead to threading
problems under certain conditions, as described in the article above.

Additional query words: prodsna

======================================================================
Keywords          : kbnetwork kbprogramming 
Technology        : kbAudDeveloper kbSNAServSearch kbSNAServ300 kbSNAServ200 kbSNAServ211 kbSNAServ400 kbSNAServ210 kbSNAServ211SP1 kbSNAServ211SP2 kbSNAServ300SP3 kbSNAServ300SP1 kbSNAServ400SP1 kbSNAServ400SP2 kbSNAServ300SP2
Version           : WINDOWS:2.0,2.1,2.11,2.11 SP1,2.11 SP2,3.0,3.0 SP1,3.0 SP2,3.0 SP3,4.0,4.0 SP1,4.0 SP2

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

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.