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FIX: Blocking problems may occur when you use SQL Server to store ASP.NET session state information for a Web site that experiences high loads
Article ID: 939866 - View products that this article applies to.
Important This article contains information about how to modify the registry. Make sure that you back up the registry before you modify it. Make sure that you know how to restore the registry if a problem occurs. For more information about how to back up, restore, and modify the registry, click the following article number to view the article in the Microsoft Knowledge Base:
(http://support.microsoft.com/kb/256986/ )Description of the Microsoft Windows registry
Consider the following scenario. You use Microsoft SQL Server to store Microsoft ASP.NET session state information for a Web site. The Web site experiences high loads. In this scenario, blocking problems may occur. This problem occurs especially when multiple requests come from the same SessionID value.
This problem occurs because the ASP.NET application tries to communicate with the computer that is running SQL Server. The connection is rejected by the computer that is running SQL Server because of blocking problems in the ASPState database. However, according to the polling mechanism, the ASP.NET application tries to communicate with the computer that is running SQL Server until the connection is accepted. This may cause an excessive, long-term blocking chain in the database. Under typical circumstances, the computer that is running SQL Server handles the initial blocking correctly. However, the high frequency of callbacks causes a snowball effect, and all the SQL threads are occupied. Therefore, manual intervention is required to clear the blocking chain.
Hotfix informationA supported hotfix is now available from Microsoft. However, it is intended to correct only the problem that is described in this article. Apply it only to systems that are experiencing this specific problem. This hotfix may receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next Microsoft .NET Framework 2.0 service pack that contains this hotfix.
To resolve this problem immediately, contact Microsoft Customer Support Services to obtain the hotfix. For a complete list of Microsoft Customer Support Services telephone numbers and information about support costs, visit the following Microsoft Web site:
http://support.microsoft.com/contactus/? ws=supportNote 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.
PrerequisitesYou must have the Microsoft .NET Framework 2.0 and Microsoft Windows Server 2003 Service Pack 1 (SP1) installed to apply this hotfix.
Restart requirementYou do not have to restart the computer after you apply this hotfix.
Hotfix replacement informationThis hotfix does not replace any other hotfixes.
File informationThis hotfix is included in hotfix 941386. For more information, click the following article number to view the article in the Microsoft Knowledge Base:
941386This hotfix introduces the following registry key. This registry key allows you to update how often to poll SQL Server:
(http://support.microsoft.com/kb/941386/ )FIX: Error message when you run an ASP.NET 2.0 Web application that is built on the .NET Framework 2.0 after you install the MS07-040 security update: "Type 'System.Web.HttpHeaderCollection' is not marked as serializable"
Note If your application runs as a 32-bit application on a 64-bit server, then the registry subkey is as follows:
Value Name: SessionStateLockedItemPollInterval
Default: 500 (in milliseconds)
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
For more information, click the following article number to view the article in the Microsoft Knowledge Base:
(http://support.microsoft.com/kb/824684/ )Description of the standard terminology that is used to describe Microsoft software updates