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Application Pools

Published: February 29, 2012

Updated: February 29, 2012

Applies To: Windows Server 2012, Windows Server 2012 R2



Use the Application Pools feature page to manage a list of application pools on a Web server.

Sort the list by clicking one of the column headings on the feature page or select a value from the Group by drop-down list to group similar items. Search the list by typing search criteria in the Filter box, expand the Go list to select the field on which to search, and then click Go or press ENTER. Click Show All to remove the filter criteria.

Related scenarios

In this document

The following tables describe the UI elements that are available on the feature page and in the Actions pane.

 

Element Name Description

Name

Displays the name of each application pool.

Status

Displays whether an application pool is started.

.NET Framework Version

Displays the version of the .NET Framework that an application pool uses. If the application pool was configured to not use the .NET Framework, the value is No Managed Code.

Managed Pipeline Mode

Displays the request-processing mode that an application pool uses.

Values can be Integrated or Classic. When the value is Integrated, IIS uses the integrated IIS and ASP.NET request-processing pipeline to process requests in the application pool. When the value is Classic, IIS uses separate IIS and ASP.NET request-processing pipelines to process requests in the application pool.

Identity

Displays the identity used by an application pool. Values can be Network Service, Local Service, Local System, or the name of the user account for a custom identity.

Applications

Displays the number of applications that an application pool contains.

 

Element Name Description

Add Application Pool

Opens the Add Application Pool dialog box from which you can add an application pool to the Web server.

Set Application Pool Defaults

Opens the Application Pool Defaults dialog box from which you can set default values that apply to all application pools that you add to the web server.

When you select a setting on the dialog box, a description of the setting appears at the bottom.

Start

Starts the selected application pool.

Stop

Stops the selected application pool. And causes the Windows Process Activation Service (WAS) to shut down all running worker processes serving that application pool. An administrator must restart a stopped application pool or else requests made to applications in that application pool will receive HTTP 503-Service Unavailable errors.

Recycle

Stops and restarts the selected application pool. Restarting an application pool causes the application pool to be temporarily unavailable until the restart is complete.

Basic Settings

Opens the Edit Application Pool dialog box from which you can edit the settings that were specified when the application pool was created. This action is available only when an item is selected from the list on the feature page.

Recycling

Opens the Edit Application Pool Recycling Settings wizard from which you can specify conditions under which to recycle an application pool and configure how recycling events are logged.

Advanced Settings

Opens the Advanced Settings dialog box from which you can configure advanced settings for the selected application pool.

Rename

Enables the Name field of the selected application pool so that you can rename the application pool.

Remove

Removes the item that is selected from the list on the feature page.

noteNote
You cannot remove an application pool that contains applications. You must move any applications out of the application pool before you can remove it.

View Applications

Opens the Applications feature page from which you can view the applications that belong to the selected application pool.

Use the Add Application Pool and Edit Application Pool dialog boxes to create or edit an application pool. An application pool is a group of one or more URLs that are served by a worker process or a set of worker processes. Application pools set boundaries for the applications that they contain; these boundaries prevent applications in one application pool from affecting applications in another application pool.

 

Element Name Description

Name

Type a unique, friendly name for your application pool. You can use this name to identify the application pool later, and to simplify the assignment of applications to the application pool.

noteNote
You cannot rename an application pool from the Edit Application Pool dialog box. To rename an application pool, use the Rename action in the Actions pane on the Application Pools feature page.

.NET Framework version

Select the version of the .NET Framework that is loaded by this application pool. If the applications that you want to assign to this application pool do not contain managed code, select the No Managed Code option from the list.

An application pool can load only one version of the .NET Framework; all applications in the application pool must use the same version.

noteNote
If you select .NET Framework version 1.1, the Managed pipeline mode list will be disabled. Additionally, if you are running IIS 8 on 64-bit Windows, and you have installed .NET Framework version 1.1, the value will not appear in the .NET Framework Version list when you add or edit an application pool. This is because .NET Framework version 1.1 installs under the Framework directory, but IIS reads values from the Framework64 directory on 64-bit Windows. You must set the managedRuntimeVersion attribute to v1.1 for the application pool in the configuration file directly or by using a tool such as Appcmd.exe.

Managed pipeline mode

Select one of the following values from the list to specify how IIS processes requests for managed content:

  • Integrated - IIS processes requests for managed content with the integrated IIS and ASP.NET request-processing pipeline.

  • Classic - IIS processes requests for managed content with the separate IIS and ASP.NET request-processing pipelines. Use this mode only when the applications in the application pool cannot run in Integrated mode.

Start application pool immediately

Select this option to enable the application pool to start whenever the Windows Process Activation Service (WAS) is started. If you disable automatic startup, you must start the application pool manually or else requests made to applications in the application pool will return an HTTP 503-Service Unavailable error.

Use the Application Pool Identity dialog box to configure the account under which an application pool's worker process runs. You can select one of the predefined security accounts or configure a custom account.

noteNote
If you use a custom identity, make sure that the user account you specify is a member of the IIS_IUSRS group on the Web server so that the account has proper access to resources. Additionally, when you use Windows and Kerberos authentication in your environment, you might need to register a Service Principle Name (SPN) with the domain controller (DC).

  1. On the Application Pools feature page, select an application pool from the list.

  2. In the Actions pane, click Advanced Settings.

  3. Under Process Model, locate the Identity field and click (the Properties button) to open the Application Pool Identity dialog box.

  4. Select an identity option:

    • Select Built-in account to use a predefined security account, and then select one of the accounts from the list.

    • Select Custom account to configure a custom account, and then click Set to open the Set Credentials dialog box from which you can specify the user name and password for the account.

 

Element Name Description

Built-in account

Select this option to use one of the predefined security accounts. Then select one of the following accounts:

  • LocalService - The Local Service account is a member of the Users group and has the same user rights as the Network Service account, but the Local Service account is limited to the local computer. Use this account when the worker process in your application pool does not require access outside the Web server on which it runs.

  • LocalSystem - The Local System account has all user rights, and it is part of the Administrators group on the Web server. Whenever possible, avoid using the Local System account because it presents a more serious security risk for your Web server.

  • NetworkService - By default, the Network Service account is selected. It is a member of the Users group and has user rights that are required to run applications. It can interact throughout an Active Directory-based network by using the credentials of the computer account. This account provides the most security against an attack that might try to take over the Web server.

Custom account

Select this option to configure a custom account. Then click the corresponding Set button to configure the user name and password for the account.

Set

Opens the Set Credentials dialog box from which you can specify credentials for the custom account.

User name

Type the alias of the user account under which you want the worker process to run.

Password

Type the password for the user account that you specified in the User name box.

Confirm password

Retype the password for the user account that you specified in the User name box.

Use the Recycling Conditions page of the Edit Application Pool Recycling Settings Wizard to configure IIS to periodically restart worker processes in an application pool. Restarting worker processes can help you to recover valuable system resources and to manage faulty worker processes better.

 

Element Name Description

Regular time intervals (in minutes)

Select this option to specify a time interval, in minutes, at which you want IIS to recycle the worker process. You might choose this option if you have an application that causes problems when it runs for an extended time. Based on what you know about the application, you should set the value to be less than the length of time elapsed before application failure.

Fixed number of requests

Select this option to specify the number of requests after which you want IIS to recycle the worker process. You might choose this option if you have an application that causes problems after reaching a certain number of requests. Based on what you know about the application, you should configure the value to be less than the number of requests processed before application failure.

Specific time(s)

Select this option to specify a time or times at which you want IIS to recycle the worker process in a 24-hour period. For example, to recycle a worker process at 4:30 A.M. and 4:30 P.M., enter 4:30 AM, 4:30 PM. The time that you specify uses the local time on the Web server. You might choose this option if you have an application that causes problems when it runs for an extended time and you want to recycle the application pool at a specific time, such as a time that is late at night or early in the morning, to avoid a negative impact on users. Based on what you know about the application, you should set the interval to be frequent enough to prevent application failure.

Virtual memory usage (in KB)

Select this option to specify the maximum number of kilobytes of your system's common virtual memory that can be used by a worker process before that process is recycled. You might choose this option when you notice a steady increase in the virtual memory used on your server. This might indicate that an application reserves memory multiple times, which fragments the memory heap. Entering too high a value can severely decrease system performance. At first, you should set the virtual memory threshold to be less than 70 percent of available virtual memory, and then adjust the setting if you have to.

Private memory usage (in KB)

Select this option to specify the maximum privately allocated system physical memory that a worker process can use before the process is recycled. You might choose this option when you have an application that leaks memory. Entering too high a value can severely decrease system performance. At first, you should set this value to be less than 60 percent of the available physical memory on the server, and then adjust this setting if you have to.

Use the Recycling Events to Log page of the Edit Application Pool Recycling Settings Wizard to configure IIS to log an event when a worker process is recycled.

You can configure IIS to log recycling events that you set up, such as at a fixed interval. You can also configure IIS to log recycling events that occur at runtime, such as when an ISAPI declares itself unhealthy.

 

Element Name Description

Regular time intervals

Select this option to log an event when a worker process is recycled at a specified time interval. This option is available only when the Regular time intervals (in minutes) option is selected and a time interval is specified on the previous wizard page.

Virtual memory usage

Select this option to log an event when a worker process is recycled after using a specified amount of virtual memory. This option is available only when the Virtual memory usage (in KB) option is selected and a number of kilobytes is specified on the previous wizard page.

Number of requests

Select this option to log an event when a worker process is recycled after reaching a specified number of requests. This option is available only when the Fixed number of requests option is selected and a number of requests is specified on the previous wizard page.

Scheduled time(s)

Select this option to log an event when a worker process is recycled at a specified time. This option is available only when the Specific time(s) option is selected and a time is specified on the previous wizard page.

Private memory usage

Select this option to log an event when a worker process is recycled after using a specified amount of physical memory. This option is available only when the Private memory usage (in KB) option is selected and a number of kilobytes is specified on the previous wizard page.

On-demand

Select this option to log an event when you recycle a worker process by using IIS Manager or Appcmd.exe to correct a problem.

Configuration changes

Select this option to log an event when a change to configuration causes the application pool to recycle.

Unhealthy ISAPI

Select this option to log an event when an ISAPI extension reports to the worker process that it is unhealthy.

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