Recycling Settings for an Application Pool <recycling>

Overview

The <recycling> element contains configuration settings that control the conditions that trigger IIS 7 to restart an application pool. You can also control the types of events IIS writes to the event log when the application pool recycles.

You can specify that IIS recycle an application pool at set intervals (such as every 180 minutes), at a specific time each day, or after the application pool receives a certain number of requests. You can also configure the <recycling> element to restart the application pool when the worker process virtual memory and physical memory usage reaches a specific threshold.

You can use the <recycling> element to specify two classes of events to log to the event log when IIS recycles an application pool. The first class contains recycling events that you can configure, such as those mentioned in the previous paragraph. The second class includes run-time recycling events, such as on-demand recycling events, recycling events triggered by configuration changes in the application or applications running in the application pool, or recycling caused by an unhealthy Internet Server Application Programming Interface (ISAPI) filter or ISAPI extension.

The <recycling> element uses the following attribute and child element to implement these features:

• logEventOnRecycle attribute
• periodicRestart element

Compatibility

Version	Notes
IIS 8.5	The <recycling> element was not modified in IIS 8.5.
IIS 8.0	The <recycling> element was not modified in IIS 8.0.
IIS 7.5	The <recycling> element was not modified in IIS 7.5.
IIS 7.0	The <recycling> element was introduced in IIS 7.0.
IIS 6.0	The <recycling> element replaces portions of the IIS 6.0 IIsApplicationPools metabase property.

Setup

The <applicationPools> collection is included in the default installation of IIS 7.

How To

HOW TO SET UP PERIODIC RECYCLING FOR AN APPLICATION POOL

1. Open Internet Information Services (IIS) Manager:
   • If you are using Windows Server 2012 or Windows Server 2012 R2:
     • On the taskbar, click Server Manager, click Tools, and then click Internet Information Services (IIS) Manager.
   • If you are using Windows 8 or Windows 8.1:
     • Hold down the Windows key, press the letter X, and then click Control Panel.
     • Click Administrative Tools, and then double-click Internet Information Services (IIS) Manager.
   • If you are using Windows Server 2008 or Windows Server 2008 R2:
     • On the taskbar, click Start, point to Administrative Tools, and then click Internet Information Services (IIS) Manager.
   • If you are using Windows Vista or Windows 7:
     • On the taskbar, click Start, and then click Control Panel.
     • Double-click Administrative Tools, and then double-click Internet Information Services (IIS) Manager.
2. In the Connections pane, expand the server name, and then click Application Pools.
3. In the Application Pools pane, select the application pool you want edit.
4. In the Actions pane, click Recycling... 
   
5. On the Recycling Conditions page of the Edit Application Pool Recycling Settings Wizard, select at least one of the options in the Fixed Intervals section, type values into the appropriate text boxes, and then click Next.
   
6. (Optional) On the Recycling Events to Log page of the Edit Application Pool Recycling Settings Wizard, select the configurable recycling events and run-time recycling events that you want IIS to send to the event log when they occur, and then click Finish.
   

   Note: By default, IIS sends the Regular time intervals, Virtual memory usage, and Private memory usage configurable recycling events to the event log. The other configurable recycling events are available for logging only if you have enabled the logging event on the Recycling Conditions page.

Configuration

The <recycling> element is configurable at the server level in the ApplicationHost.config file.

ATTRIBUTES

Attribute

Description

disallowOverlappingRotation

Optional Boolean attribute.

Specifies whether the WWW Service should start another worker process to replace the existing worker process while that process is shutting down. The value of this property should be set to true if the worker process loads any application code that does not support multiple worker processes.

The default value is false.

disallowRotationOnConfigChange

Optional Boolean attribute.

Specifies whether the WWW Service should rotate worker processes in an application pool when the configuration has changed.

The default value is false.

logEventOnRecycle

Optional flags attribute.

Specifies that IIS should log an event when an application pool is recycled. ThelogEventOnRecycle property must have a bit set corresponding to the reason for the recycle if IIS is to log the event.

The logEventOnRecycle attribute can have one or more of the following possible values. If you specify more than one value, separate them with a comma (,). The default values are Time, Memory, and PrivateMemory.

Value	Description
ConfigChange	Log an event when an application pool recycles because of a configuration change. The numeric value is 64.
IsapiUnhealthy	Log an event when an application pool recycles after an ISAPI extension reports to the worker process that it is in an unhealthy state.  The numeric value is 16.
Memory	Log an event when an application pool recycles after it uses a specified amount of virtual memory. The numeric value is 8.
OnDemand	Log an event when an application pool is recycled immediately to correct a problem. The numeric value is 32.
PrivateMemory	Log an event when an application pool recycles after it uses a specified amount of virtual memory. The numeric value is 128.
Requests	Log an event when an application pool recycles after it reaches a configured number of requests. The numeric value is 2.
Schedule	Log an event when an application pool recycles after it reaches a configured time of day. The numeric value is 4.
Time	Log an event when an application pool recycles after a configured time. The numeric value is 1.

CHILD ELEMENTS

Element	Description
periodicRestart	Optional element. Specifies conditions under which application pools are recycled.

CONFIGURATION SAMPLE

The following configuration sample uses the application pool <add> element to create a new application pool named Contoso. The <recycling> element configures logging for application pool restarts, the <periodicRestart> element configures when the application pool restarts, and the <processModel> element configures the shutdownTimeLimit and startupTimeLimitattributes for shutting down and starting the worker processes in the application pool for 30 seconds each. If these time limits are exceeded, IIS terminates the worker process.

<add name="Contoso">
   <recycling logEventOnRecycle="Schedule">
      <periodicRestart>
         <schedule>
            <clear />
            <add value="03:00:00" />
         </schedule>
      </periodicRestart>
   </recycling>
   <processModel identityType="NetworkService" shutdownTimeLimit="00:00:30" startupTimeLimit="00:00:30" />
</add>

Sample Code

The following code examples add an application pool named Contoso to your IIS 7 server, then set the application pool to daily recycle at 3:00 A.M.

APPCMD.EXE

appcmd.exe set config -section:system.applicationHost/applicationPools /+"[name='Contoso']" /commit:apphost
 
appcmd.exe set config -section:system.applicationHost/applicationPools /+"[name='Contoso'].recycling.periodicRestart.schedule.[value='03:00:00']" /commit:apphost

You can also use the following syntax:

appcmd.exe add apppool /name:"Contoso"
 
appcmd.exe set config -section:system.applicationHost/applicationPools /+"[name='Contoso'].recycling.periodicRestart.schedule.[value='03:00:00']" /commit:apphost

Note: You must be sure to set the commit parameter to apphost when you use AppCmd.exe to configure these settings. This commits the configuration settings to the appropriate location section in the ApplicationHost.config file.

C#

using System;
using System.Text;
using Microsoft.Web.Administration;
 
internal static class Sample
{
   private static void Main()
   {
      using (ServerManager serverManager = new ServerManager())
      {
         Configuration config = serverManager.GetApplicationHostConfiguration();
         ConfigurationSection applicationPoolsSection = config.GetSection("system.applicationHost/applicationPools");
         ConfigurationElementCollection applicationPoolsCollection = applicationPoolsSection.GetCollection();
         ConfigurationElement addElement = applicationPoolsCollection.CreateElement("add");
         addElement["name"] = @"Contoso";
         ConfigurationElement recyclingElement = addElement.GetChildElement("recycling");
         ConfigurationElement periodicRestartElement = recyclingElement.GetChildElement("periodicRestart");
         ConfigurationElementCollection scheduleCollection = periodicRestartElement.GetCollection("schedule");
         ConfigurationElement addElement1 = scheduleCollection.CreateElement("add");
         addElement1["value"] = TimeSpan.Parse("03:00:00");
         scheduleCollection.Add(addElement1);
         applicationPoolsCollection.Add(addElement);
         serverManager.CommitChanges();
      }
   }
}

VB.NET

Imports System
Imports System.Text
Imports Microsoft.Web.Administration
 
Module Sample
   Sub Main()
      Dim serverManager As ServerManager = New ServerManager
      Dim config As Configuration = serverManager.GetApplicationHostConfiguration
      Dim applicationPoolsSection As ConfigurationSection = config.GetSection("system.applicationHost/applicationPools")
      Dim applicationPoolsCollection As ConfigurationElementCollection = applicationPoolsSection.GetCollection
      Dim addElement As ConfigurationElement = applicationPoolsCollection.CreateElement("add")
      addElement("name") = "Contoso"
      Dim recyclingElement As ConfigurationElement = addElement.GetChildElement("recycling")
      Dim periodicRestartElement As ConfigurationElement = recyclingElement.GetChildElement("periodicRestart")
      Dim scheduleCollection As ConfigurationElementCollection = periodicRestartElement.GetCollection("schedule")
      Dim addElement1 As ConfigurationElement = scheduleCollection.CreateElement("add")
      addElement1("value") = TimeSpan.Parse("03:00:00")
      scheduleCollection.Add(addElement1)
      applicationPoolsCollection.Add(addElement)
      serverManager.CommitChanges()
   End Sub
End Module

JAVASCRIPT

var adminManager = new ActiveXObject('Microsoft.ApplicationHost.WritableAdminManager');
adminManager.CommitPath = "MACHINE/WEBROOT/APPHOST";
var applicationPoolsSection = adminManager.GetAdminSection("system.applicationHost/applicationPools", "MACHINE/WEBROOT/APPHOST");
var applicationPoolsCollection = applicationPoolsSection.Collection;
 
var addElement = applicationPoolsCollection.CreateNewElement("add");
addElement.Properties.Item("name").Value = "Contoso";
var recyclingElement = addElement.ChildElements.Item("recycling");
var periodicRestartElement = recyclingElement.ChildElements.Item("periodicRestart");
var scheduleCollection = periodicRestartElement.ChildElements.Item("schedule").Collection;
var addElement1 = scheduleCollection.CreateNewElement("add");
addElement1.Properties.Item("value").Value = "03:00:00";
scheduleCollection.AddElement(addElement1);
applicationPoolsCollection.AddElement(addElement);
 
adminManager.CommitChanges();

VBSCRIPT

Set adminManager = createObject("Microsoft.ApplicationHost.WritableAdminManager")
adminManager.CommitPath = "MACHINE/WEBROOT/APPHOST"
Set applicationPoolsSection = adminManager.GetAdminSection("system.applicationHost/applicationPools", "MACHINE/WEBROOT/APPHOST")
Set applicationPoolsCollection = applicationPoolsSection.Collection
 
Set addElement = applicationPoolsCollection.CreateNewElement("add")
addElement.Properties.Item("name").Value = "Contoso"
Set recyclingElement = addElement.ChildElements.Item("recycling")
Set periodicRestartElement = recyclingElement.ChildElements.Item("periodicRestart")
Set scheduleCollection = periodicRestartElement.ChildElements.Item("schedule").Collection
Set addElement1 = scheduleCollection.CreateNewElement("add")
addElement1.Properties.Item("value").Value = "03:00:00"
scheduleCollection.AddElement(addElement1)
applicationPoolsCollection.AddElement(addElement)
 
adminManager.CommitChanges()