How to recycle IIS 5.0 with the IIS 5.0 Process Recycling tool

This step-by-step article describes how to download and use the Internet Information Services (IIS) 5.0 Process Recycling Tool (IIS5Recycle) version 1.0, which was released in June 2001.

Introduction

IIS5Recycle version 1.0 runs as a service on a computer that is running Microsoft Windows 2000 and IIS 5.0. The purpose of IIS5Recycle is to recycle processes, minimizing the effects of resource-consumption problems before performance and reliability are affected. This tool automatically recycles IIS processes based on configurations that are stored in the Windows registry. With IIS5Recycle, administrators can also gather information for use in troubleshooting processes and applications.

The following example illustrates how IIS5Recycle can be used to recycle processes and to gather information:

Minimizing consumption caused by memory leaks:

A Web administrator suspects that Web applications that are running on the servers are leaking memory. The administrator schedules periodic recycling of IIS processes to release resources that are consumed by the leaking Web applications. The administrator can troubleshoot a Web application by using the Advanced Scripting feature. The administrator gathers and logs information about a problematic Web application before IIS is recycled. While the Web site continues to serve the customer, a developer can analyze the logs.

Installation instructions

To install IIS5Recycle:

1. Create a directory on drive C named IIS5Recycle:
   1. On the Windows 2000 desktop, right-click My Computer, and then click Explore.
   2. Click to select drive C.
   3. On the File menu, click New, and then click Folder. In the right pane, a folder named New Folder appears and is selected.
   4. Type IIS5Recycle, and then press ENTER. This renames the New Folder folder to IIS5Recycle.
2. Download IIS5Recycle.exe to your computer and extract the files to the C:\IIS5Recycle directory: The following file is available for download from the Microsoft Download Center:
   
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   Download the IIS5Recycle.exe package now. (http://www.microsoft.com/downloads/details.aspx?FamilyID=c4ba5f3c-1eb2-4f3c-99b0-b0cde072a7d8&DisplayLang=en) For additional information about how to download Microsoft Support files, click the following article number to view the article in the Microsoft Knowledge Base:
   119591  (http://support.microsoft.com/kb/119591/ ) How to Obtain Microsoft Support Files from Online Services
   Microsoft scanned this file for viruses. Microsoft used the most current virus-detection software that was available on the date that the file was posted. The file is stored on security-enhanced servers that help to prevent any unauthorized changes to the file.
3. Open a command prompt and change to the IIS5Recycle directory.
4. Type IIS5Recycle /install.
5. Type IIS5Recycle /config to configure the recycling conditions. To select the IIS recycle configuration options, click to select the check box for the particular option that you want to use. When you select one or more options, you must supply a number (that is, a value) for each option. For more information about the configuration options, see the "Functionality and Configuration" section.
   
   
6. For more information about the configuration options, see the "Functionality and Configuration" section.Set your recycle options, and then type net start IIS5recycle to start the IIS5Recycle service.Note You must restart your computer for the registry keys to appear.
   
   Note You can stop the IIS5Recycle service by typing net stop IIS5recycle.

Functionality and configuration

With IIS5Recycle, administrators can set criteria for the automatic recycling of IIS processes and stop IIS when recycling fails. The default interval between the time that the IIS5Recycle tools checks these values is either 15 minutes or what the QueryIISMinutes key is set to in the registry.

Configure IIS5Recycle

IIS5Recycle automatically recycles IIS processes based on the following criteria:

• IIS up time: Recycles IIS after it has been running for a configured number of hours.
• Total HTTP requests served: Recycles IIS based on the total number of requests served, as recorded by the Get Request performance counter.
• Time of day or week: Recycles IIS based on a specific day or time. To configure this option, click Add, click either Daily or Weekly, and then type a time based on a 24:00 clock. If you click Weekly, you must also select a day of the week (Monday through Sunday) and a number of weeks before IIS is recycled on the selected day. For example, you can configure the IIS5Recycle tool to run every two weeks on Sunday at 22:59.
  
  To remove a date or time setting, click Remove.
  
  To modify a date or time setting, click Edit.
  
  
• To configure this option, click Virtual memory usage: Recycles IIS based on the total virtual memory usage that is recorded by Inetinfo.exe and by Dllhost.exe for out-of-process applications.
• To configure this option, click ASP requests queued: Recycles IIS if the total number of Active Server Pages (ASP) requests that are queued is greater than the configured value after a determined number of retries.
  
  You can configure retries by adding a registry key named ASPThresholdRetries. For more information about how to add and set this key, see the "Registry Settings" section.
• To configure this option, click Recycle IIS at the next quiet time: Recycles the IIS service at the next quiet time threshold. To configure this setting, add and set a registry key named QuietTimeRequests. The default value is 10, which means that a quiet time occurs whenever the GET requests per second fall to 10 or lower. For more information about how to add and set registry keys, see the "Registry Settings" section. Note that you must restart your computer after you install the tool for the registry keys to appear.

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Stop IIS with IIS5Recycle

IIS5Recycle forcefully stops IIS if a recycle request is unsuccessful after a configurable amount of time. This functionality makes sure that IIS is recycled when a recycle threshold is met. The registry key for this feature is IISStopTimeoutSecs.

NoRealRecycle feature

With the NoRealRecycle feature, you can run the IIS5Recycle tool in an audit-only mode without interrupting the IIS service. When you use the audit-only mode, IIS recycling events are stored in the Windows event log and can be used to assess IIS recycling conditions that can be configured for your Web server. An administrator can use this feature to fine-tune the recycle settings based on application and environment specifics that are gathered during the audit-only mode run. To turn on this feature, add the following registry value: To turn off this feature, set the NoRealRecycle key to 0 in the registry.

Advanced Control/Scripting feature

With the Advanced Control/Scripting feature, administrators can specify commands (or scripts) to run before and after each IIS5Recycle execution.

On the IIS5Recycle screen, click Advanced to open the Advanced Control window. In the resulting window, you can add commands to run before or after IIS is recycled, and you can also add a timeout value for these commands.

The return value of the Before Command section is verified if the Verify Return Value check box is selected. The output of the script is redirected to a log file under %windir%\System32\Logfiles\Iis5recycle. If the script does not return the expected value, the current recycle is skipped.

Note On a system that uses Windows Load Balancing Service (WLBS), the script is executed after WLBS stops and before WLBS starts.

If you do not see the expected output in the log file, verify that the script name is correct and that it is copied to the %windir%\system32 directory. If the script must access any other executable files, make sure that all of those files are also located in the %windir%\system32 directory.

NLB support

IIS5Recycle removes the Web server from the cluster (Web farm) on a system that is using Windows Network Load Balancing (NLB) before it recycles the IIS process. Each time a server is taken out of a cluster, connections to the Web server are drained. After the connection number drops below the configured threshold or the specified time passes, the IIS service is recycled. You can configure the default behavior of this feature by adding and setting the following registry keys:

• %WLBSDrainWaitSecs%
• %WLBSDrainStopConnectionNum%
• %WLBSWaterMark%

See the "Appendix: Registry Settings" section for more information about these values.

The WaterMark feature guarantees that the number of servers in the cluster will always be more than the value that is set for WLBSWaterMark in the registry. There are two requirements to use the WaterMark feature:

• The remote control on each WLBS host must be turned on. If a password is required for remote control, each node must use the same password.
• NLB Web farms that do not use WLBS must be able to use the Advance Control/Scripting feature.

Recovery

The Service Control Manager (SCM), which is available through the Computer Management MMC snap-in, can be configured to take an action when a service fails unexpectedly. The IIS5Recycle service uses this feature as a fatal error notification and recovery method. When you configure the recovery actions for the IIS5Recycle service, the administrator is notified if an unrecoverable event occurs on the Web server. If any of the following failures occur, the IIS5Recycle service terminates itself to do the SCM recovery actions:

• An IIS process stops and IIS5Recycle cannot start it after several retries.
• On a system that uses clustering, the server is removed from the cluster, and IIS5Recycle cannot restart WLBS.

In both cases, an event is logged in the Windows event log.

Appendix: Registry settings

Warning If you use Registry Editor incorrectly, you may cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that you can solve problems that result from using Registry Editor incorrectly. Use Registry Editor at your own risk. All IIS5Recycle configuration settings are stored in the registry under the following key: IIS5Recycle picks up all registry changes automatically.

You can configure the following entries by using the user interface in the IIS5Recycle Tool:

Name: RunningHours
Type: REG_DWORD
Description: Recycles an IIS process every specified number of hours.
Default: 24 * 7 (No Recycle)

Name: RequestNumber
Type: REG_DWORD
Description: Recycles an IIS process every specified number of received HTTP requests.
Default: 200,000 Requests

Name: TimeSchedule
Type: REG_SZ
Description: Recycles an IIS process at certain times of a day.
Default: Blank (No Recycle schedule)

Name: MemoryUsage
Type: REG_DWORD
Description: Recycles an IIS process if it uses more than a specified amount of memory (in KB).
Default: 1000000 KB

Name: ASPRequestsQueued
Type: REG_DWORD
Description: Recycles an IIS process if the value of ASP requests queued is over this specified value in ASPThresholdRetries.
Default: 2,000

Name: CustomScriptAfter
Type: REG_SZ
Description: Runs this script after the IIS process is recycled.
Default: Blank

Name: CustomScriptBefore
Type: REG_SZ
Description: Runs this script before the IIS process is recycled.
Default: Blank

Name: CustomScriptTimeout
Type: REG_DWORD
Description: The time that is permitted for the custom scripts to run before or after the IIS process is recycled.
Default: 300 seconds

The following are the names, types, and default values of the registry entries that IIS5Recycle uses. Note that you can only configure these settings by using the registry. You cannot configure these settings by using the user interface for the IIS5Recycle Tool.

Note Your computer must be running Microsoft Windows 2000 Server with IIS 5.0 to add these registry entries.

Name: QueryIISMinutes
Type: REG_DWORD
Description: Indicates how frequently processes query IIS status.
Default: 15 minutes

Name: RecycleIISDelayMinutes
Type: REG_DWORD
Description: Indicates how long to wait to see if IIS can reach a quiet time that is defined by QuietTimeRequests if a recycle condition is reached.
Default: 0 minutes (recycle immediately)

Name: QuietTimeRequests
Type: REG_DWORD
Description: Used to determine if IIS reached the quiet time. IIS tries to recycle processes at the next quiet time (if RecycleIISDelayMinutesequals zero) if a recycle condition is reached.
Default: 10 GET requests/second

Name: IISStopTimeOutSecs
Type: REG_DWORD
Description: Indicates the time specified for IIS to stop before a timeout occurs.
Default: 60 seconds

Name: IISStartTimeOutSecs
Type: REG_DWORD
Description: Indicates the time specified for IIS to start before a timeout occurs.
Default: 60 seconds

Name: NoRealRecycle
Type: REG_DWORD
Description: Reports a recycle event only.
Default: 0 (do a recycle)

Name: WLBSDrainWaitSecs
Type: REG_DWORD
Description: Indicates the time specified for a WLBS drain to stop.
Default: 60 seconds

Name: WLBSWaterMark
Type: REG_DWORD
Description: Indicates the number of current active hosts the NLB cluster must have to prevent IIS from skipping the current recycle period. IIS skips the recycle period if the number of current active hosts in the NLB cluster is equal to or below this threshold.
Default: 0 (disabled)

Name: WLBSDrainStopConnectionNum
Type: REG_DWORD
Description: Indicates the minimum number of current connections for IIS5Recycle to stop draining. IIS5Recycle stops draining if the number of current connections is below this value.
Default: 0 (drain until there are no connections)

Name: ForceDrainStop
Type: REG_DWORD
Description: Prevents NLB from being started by other monitoring programs during the WLBSDrainWaitSecs period.
Default: 0 (disabled)

Name: ASPThresholdRetries
Type: REG_DWORD
Description: Indicates how many times IIS5Recycle retries when the number of ASP requests queued is above the set value of ASPRequestsQueued.
Default: 0 (no retries)

To add these entries, follow these steps:

1. Start Registry Editor (Regedt32.exe).
2. Locate and then click the following key in the registry:
   HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\IIs5Recycle
3. On the Edit menu, click Add Value, and then add the registry key names and values as needed:
   Value name: Name
   Data type: REG_DWORD
   Value data: Value
   Note Value specifies the value that you want to set for each registry setting. Make sure that you click Decimal before you type the value.
   
   
4. Quit Registry Editor.

For more information, visit the following Microsoft TechNet Web sites: