A Race Condition During a Remote Read Operation Causes a Stop Error (826929)


The information in this article applies to:

  • Microsoft Message Queuing 2.0

SYMPTOMS

A stop error may occur in the Mqac.sys driver after you apply the Microsoft Message Queuing hotfix that is discussed in the following Microsoft Knowledge Base article:

822835 Event ID 2085 "Unable to Create Message File ..."

CAUSE

This problem occurs because a race condition on the client side of a remote read operation permits a cursor to be closed before the remote read operation closes.

RESOLUTION

Hotfix Information

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:

http://support.microsoft.com/contactus/?ws=support

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.

Restart Requirement

You must restart your computer after you apply this hotfix.

File Information

The English version of this hotfix has the file attributes (or later) that are listed in the following table. The dates and times for these files are listed in coordinated universal time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time tool in Control Panel. 
   Date         Time   Version           Size     File name
   ---------------------------------------------------------------------------------------
   15-Aug-2003  16:01  5.3.18.6          637,800  Windows2000-kb826929-x86-enu-symbols.exe  
   15-Aug-2003  16:03  5.3.18.6        1,006,440  Windows2000-kb826929-x86-enu.exe  
   14-Aug-2003  23:07  5.0.0.778         281,360  Mq1repl.dll      
   17-Jun-2003  14:33  5.0.0.778          14,096  Mq1sync.exe      
   14-Aug-2003  16:02  5.0.0.782          76,144  Mqac.sys
   14-Aug-2003  23:07  5.0.0.782         217,360  Mqads.dll        
   30-Oct-2002  13:43  5.0.0.761          25,360  Mqbkup.exe       
   14-Aug-2003  23:07  5.0.0.778          76,560  Mqdscli.dll      
   14-Aug-2003  23:07  5.0.0.773          42,256  Mqdssrv.dll      
   21-Oct-2002  17:31  5.0.0.759          98,064  Mqmig.exe        
   14-Aug-2003  23:07  5.0.0.759         265,488  Mqmigrat.dll     
   14-Aug-2003  23:07  5.0.0.740         222,480  Mqoa.dll         
   14-Aug-2003  23:07  5.0.0.762           8,464  Mqperf.dll       
   14-Aug-2003  23:07  5.0.0.782         429,328  Mqqm.dll         
   14-Aug-2003  23:07  5.0.0.778         102,672  Mqrt.dll         
   14-Aug-2003  23:07  5.0.0.776          70,928  Mqsec.dll        
   14-Aug-2003  23:07  5.0.0.781         400,656  Mqsnap.dll       
   14-Aug-2003  23:07  5.0.0.762          23,824  Mqupgrd.dll      
   14-Aug-2003  23:07  5.0.0.782         110,864  Mqutil.dll       
   14-Aug-2003  23:07  5.0.0.748          64,784  Msmq.cpl


STATUS

Microsoft has confirmed that this is a problem in the Microsoft products that are listed at the beginning of this article.

MORE INFORMATION

For additional information about how hotfix packages are named, click the following article number to view the article in the Microsoft Knowledge Base:

816915 New Naming Schema for Microsoft Windows Hotfix Packages

Note This hotfix must be installed on any system running the Message Queuing service where the client is performing a remote read operation.

A remote read operation on the client side has the following phases:
  1. A packet is received from the remote side. At this point, the packet remains on the remote side.
  2. The packet is given to the Mqac.sys driver so that the run time returns from the MQReceiveMessage function.
  3. The remote side is notified to delete the packet.
If the application calls the MQCloseCursor function immediately after it returns from MQReceiveMessage to close the remote cursor and this call reaches the server side before phase 3, notification occurs without a valid cursor. If notification occurs without a valid cursor, the stop error may occur. This hotfix adds a critical section on the client side to make sure that the MQCloseCursor function reaches the server side after phase 3.
Modification Type:MinorLast Reviewed:10/25/2005
Keywords:kbHotfixServer kbQFE kbBug kbfix kbQFE kbWin2000preSP5fix KB826929 kbAudDeveloper
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