SNA Server Win32 API Calls May Not Return to Multithreaded App (159350)

The information in this article applies to:

Microsoft SNA Server 2.0
Microsoft SNA Server 2.1
Microsoft SNA Server 2.11
Microsoft SNA Server 2.11 SP1
Microsoft SNA Server 2.11 SP2
Microsoft SNA Server 3.0
Microsoft SNA Server 3.0 SP1
Microsoft SNA Server 3.0 SP2
Microsoft SNA Server 3.0 SP3
Microsoft SNA Server 4.0
Microsoft SNA Server 4.0 SP1
Microsoft SNA Server 4.0 SP2

This article was previously published under Q159350

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:

Remove the close request from the application.
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:

132078 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.

Modification Type:	Minor	Last Reviewed:	5/17/2005
Keywords:	kbnetwork kbprogramming KB159350