Article ID: 830475 - View products that this article applies to.
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A Microsoft Message Queuing (also known as MSMQ) component that uses the EnableNotification method call and is written in Microsoft Visual Basic may result in an access violation.
This access violation occurs because of a race condition between threads in the Mqoa.dll file. When this problem occurs, the running program thread calls the MSMQQueue.EnableNotification method. The message is peeked immediately and is dispatched to the MSMQEvent event handler. Because the MSMQEvent event handler is in a multithreaded apartment (MTA), the call is dispatched to a worker thread. This worker thread will execute the event handler code and may take some time to complete.
The race condition starts when the program thread exits and runs its destructor. Because the MSMQEvent event handler is an apartment thread, the release event is dispatched to the MSMQEvent event handler, and the MSMQEvent object is released from memory. In the meantime, the event handler worker thread still tries to finish processing the event message. When the worker thread tries to reference the MSMQEvent object, an access violation occurs because the MSMQEvent object has been released from memory. For additional information about race conditions, click the following article number to view the article in the Microsoft Knowledge Base:
317723For additional information about multithreaded apartments (MTA), click the following article number to view the article in the Microsoft Knowledge Base:
(https://support.microsoft.com/kb/317723/ )INFO: What Are Race Conditions and Deadlocks?
(https://support.microsoft.com/kb/150777/ )INFO: Descriptions and Workings of OLE Threading Models
Hotfix InformationA supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing this specific problem.
If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, submit a request to Microsoft Customer Service and Support to obtain the hotfix.
Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft Web site:
http://support.microsoft.com/contactus/?ws=supportNote The "Hotfix download available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.
PrerequisitesNo prerequisites are required.
Restart RequirementYou must restart your computer after you apply this hotfix.
Hotfix Replacement InformationThis hotfix does not replace any other hotfixes.
File InformationThe 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 -------------------------------------------------------------- 21-Oct-2003 14:03 188.8.131.528 281,360 Mq1repl.dll 20-Sep-2003 17:23 184.108.40.2068 14,096 Mq1sync.exe 02-Oct-2003 19:21 220.127.116.115 76,016 Mqac.sys 21-Oct-2003 14:03 18.104.22.1683 217,360 Mqads.dll 20-Sep-2003 17:23 22.214.171.1241 25,360 Mqbkup.exe 21-Oct-2003 14:03 126.96.36.1995 76,560 Mqdscli.dll 21-Oct-2003 14:03 188.8.131.523 42,256 Mqdssrv.dll 20-Sep-2003 17:23 184.108.40.2069 98,064 Mqmig.exe 21-Oct-2003 14:03 220.127.116.119 265,488 Mqmigrat.dll 21-Oct-2003 14:03 18.104.22.1687 222,480 Mqoa.dll 21-Oct-2003 14:03 22.214.171.1244 10,000 Mqperf.dll 21-Oct-2003 14:03 126.96.36.1996 433,936 Mqqm.dll 21-Oct-2003 14:03 188.8.131.528 102,672 Mqrt.dll 21-Oct-2003 14:03 184.108.40.2066 70,928 Mqsec.dll 21-Oct-2003 14:03 220.127.116.113 400,656 Mqsnap.dll 21-Oct-2003 14:03 18.104.22.1682 23,824 Mqupgrd.dll 21-Oct-2003 14:03 22.214.171.1242 110,864 Mqutil.dll 21-Oct-2003 14:03 126.96.36.1998 64,784 Msmq.cpl 09-Oct-2003 00:18 188.8.131.52 6,656 Spmsg.dll 09-Oct-2003 00:19 184.108.40.206 140,800 Spuninst.exe 09-Oct-2003 00:19 220.127.116.11 22,016 Spcustom.dll
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section of this article.
Article ID: 830475 - Last Review: October 26, 2013 - Revision: 2.6