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Q131640: 100% CPU Usage Running SNA Windows 3.x Client on Windows NT

Article: Q131640
Product(s): Microsoft SNA Server
Version(s): WINDOWS:2.0,2.1,2.11,3.0,4.0
Operating System(s): 
Keyword(s): sna4
Last Modified: 12-JUN-2001

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The information in this article applies to:

- Microsoft SNA Server, versions 2.0, 2.1, 2.11, 3.0, 4.0 
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SUMMARY
=======

When you run the SNA Server Windows 3.x client under Windows NT 3.1 or 3.5,
Performance Monitor shows CPU utilization at 100 percent. This occurs whenever
the SNA Server Windows 3.x client process (WNAP.EXE) is running, even if it is
not being used.

The WNAP process, which calls PeekMessage(), is causing the Windows NT WOW
subsystem to use all available idle CPU cycles. However, due to sophisticated
Windows NT process scheduling, other tasks/threads running at a higher priority
(including foreground tasks), and tasks/threads running at the same priority,
continue to run. You will probably not notice any performance degradation.

The excessive CPU usage does not occur under Windows NT 3.51.


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

The high CPU usage occurs on Windows NT 3.1 or 3.5 with any 16-bit Windows
application which implements a PeekMessage() loop to process Windows messages.
The SNA Server Windows 3.x client (WNAP.EXE) uses a PeekMessage() loop.


Additional query words: prodsna 2.00 2.10 3.50 CPU

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Keywords          : sna4 
Technology        : kbAudDeveloper kbSNAServSearch kbSNAServ300 kbSNAServ200 kbSNAServ211 kbSNAServ400 kbSNAServ210
Version           : WINDOWS:2.0,2.1,2.11,3.0,4.0

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