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Article ID: 257821 - Last Review: January 27, 2007 - Revision: 1.6

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This article was previously published under Q257821


The select function adds 500 milliseconds (msec) to the running time when the timeval parameter specifies 500 or more msec. This occurs when a socket is checked for readability or errors.

As a consequence, it is not possible to effectively specify a timeout of between 500 and 1000 msec.


The select function calls an internal socket provider function that does not eliminate the time used during an optimized check for blocking callbacks.


A supported hotfix is now available from Microsoft, but it is only intended to correct the problem that this article describes. Apply it only to systems that are experiencing this specific problem.

To resolve this problem, contact Microsoft Product Support Services to obtain the hotfix. For a complete list of Microsoft Product Support Services telephone numbers and information about support costs, visit the following Microsoft Web site: (
Note In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The usual support costs will apply to additional support questions and issues that do not qualify for the specific update in question.

   Date        Time    Version      Size   File name    Platform
   03/22/2000  01:08p  27,648 Msafd.dll    Windows 98
   03/22/2000  01:31p  26,624 Mswsosp.dll  Windows 98
   03/22/2000  12:44p  27,648 Msafd.dll    Windows 98 SE
   03/22/2000  12:55p  26,624 Mswsosp.dll  Windows 98 SE


Microsoft has confirmed that this is a problem in all versions of Windows 95 and Windows 98.


For additional information about Windows 98 and Windows 98 Second Edition hotfixes, click the article number below to view the article in the Microsoft Knowledge Base:
206071  ( ) General Information About Windows 98 and Windows 98 Second Edition Hotfixes

  • Microsoft Platform Software Development Kit-January 2000 Edition
  • Microsoft Windows 95
  • Microsoft Windows 98 Standard Edition
  • Microsoft Windows 98 Second Edition
kbhotfixserver kbqfe kbprb kbprogramming kbqfe KB257821
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