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Q176965: Programs (16-bit .exe) May Start NTVDM at 100% CPU Utilization

Article: Q176965
Product(s): Windows for Workgroups and Windows NT Networking Issues
Version(s): WinNT:4.0
Operating System(s): 
Keyword(s): kbinterop
Last Modified: 13-JUN-2001

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The information in this article applies to:

- the operating system: Microsoft Windows NT 4.0 
- Microsoft Internet Information Server versions 1.0, 2.0, 3.0 
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SYMPTOMS
========

Internet Information Server (IIS) does not support Web links that launch 16- bit
applications as CGI scripts. This article details a particular problem that
occurs as a result of IIS not supporting such Web links. It also explains why
the problem occurs. A symptom of the problem is a slow server showing Task
Manager with one session of Windows NT Virtual DOS Machine (NTVDM) running at
100 percent of CPU utilization.

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

At least one session of NTVDM is always associated with a launching of a 16- bit
application. Internet Information Server launches a Web page link to a 16-bit
application as a CGI script. In this case, the process is spawned by IIS to run
in a non-interactive state, with spawn parameters that do not permit the
application to receive console-user input. In the case where a 16-bit
application requests console-user input and polls the keyboard for input,
especially in a tight loop, CPU utilization may increase to 100 percent.


This problem may occur in some large Web sites where the following two things are
unclear:

1. That the same Web link points to a 16-bit application.

2. That the 16-bit application contains prompts for user input.

This issue becomes more problematic on large Web sites, where it is difficult to
determine who spawned the executable. Task Manager, which you access by
double-clicking Taskbar, only details the name NTVDM, instead of the 16-bit
executable name. To find the executable name, it is helpful to reference an IIS
generated logfile, which is contained under the \winnt\system32\LogFile
directory. This date-specific file contains a history of processes spawned by
IIS by application name.

Here is an example of the logfile contents:

  C:\WINNT\system32\LOGFILES>type in971021.log
  107.57.227.160, -, 10/21/97, 17:11:48, W3SVC, COMPUTER1, 107.57.227.160,
  681, 437, 72, 304, 0, GET, /test2.htm, -,
  107.57.227.160, -, 10/21/97, 17:11:49, W3SVC, COMPUTER1, 107.57.227.160,
  141, 429, 72, 304, 0, GET, /samples/images/backgrnd.gif, -,
  107.57.227.160, -, 10/21/97, 17:26:51, W3SVC, COMPUTER1, 107.57.227.160,
  900334, 423, 275, 502, 0, GET, /scripts/test2.exe, -,

Viewing this logfile output should make it easier to track down the name of the
16-bit spawned executables. Since spawning 16-bit executables from Web links is
not supported under IIS, it is a good idea to review all executable files under
the IIS directories.

16-bit executables show the following tabs under Windows Explorer/Properties:

  General, Program, Font, Memory, Screen, Misc
  (Example: Go to Windows Explorer and find \winnt\system32\edit.com.
  Right click and choose Properties).

32-bit executables show only the following tabs under Windows
Explorer/Properties:

  General, Version

Additional query words: prodiis 16Bit vdm dos app dosapp Zip file zip files processor util

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Keywords          : kbinterop 
Technology        : kbiisSearch kbOSWinSearch kbOSWinNT400 kbiis300 kbiis200 kbiis100 kbOSWinNTSearch
Version           : WinNT:4.0
Issue type        : kbprb
Solution Type     : kbnofix

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