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Important This article contains information about modifying the registry. Before you modify the registry, make sure to back it up and make sure that you understand how to restore the registry if a problem occurs. For information about how to back up, restore, and edit the registry, click the following article number to view the article in the Microsoft Knowledge Base:
256986 Description of the Microsoft Windows Registry
When many clients connect to Microsoft Message Queuing, also known as MSMQ, Message Queuing may exhaust its kernel-pool memory. This problem may become worse when Message Queuing executes Active Directory queries while processing incoming messages. Validating client certificates is an example of an incoming message.
This problem may occur when many Message Queuing clients connect to Message Queuing at the same time. This causes an accumulation of Transmission Control Protocol (TCP) buffers in the kernel-pool memory. This TCP buffer-pool memory accumulation is the result of many outstanding messages that are not promptly processed by Message Queuing.
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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.
You must have Service Pack 4 or later.
You must restart your computer after you apply this hotfix.
Hotfix replacement information
This hotfix does not replace any other hotfix.
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.
The hotfix that is discussed in this article limits the number of clients that can connect to Message Queuing. This hotfix adds two registry entries that may cause the client to have its connection reset when that client tries to connect to Message Queuing. This behavior occurs if the threshold is reached. The client must wait until another connection is available.The new registry entries follow:
The new registry entries are located in the following registry subkey:
Use the following table to configure the new registry entries:
This value represents the actual number of sessions that Message Queuing lets connect at the same time. When this value is -1, or if the MaxInSessions new registry entry is not present, there is no change. The number of connections is not limited.
This value represents the time interval in milliseconds that Message Queuing waits until it verifies the number of active sessions. Message Queuing does this to verify whether new sessions can be accepted. This entry only applies if the MaxInSessions new registry entry is present, and the number-of-sessions limit is reached.
When Message Queuing diagnostic logging is enabled, Message Queuing logs the following message when Message Queuing stops accepting new sessions:
QM Error: sessmgr/376, Point
When Message Queuing resumes accepting new sessions, Message Queuing logs the following message:
QM Error: sessmgr/377, Point
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
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 file naming schema for Microsoft Windows software update packages