SNA Server Win32 API Calls May Not Return to Multithreaded App

• Microsoft SNA Server version 2.0, 2.1, 2.11 and 3.0

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.

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:

   ARTICLE-ID: Q132078
   TITLE: How to Use _beginthreadex() and _endthreadex()