IIS Application Pool Recycling
Applies To: Windows Server 2008 R2
Internet Information Services (IIS) application pools can be periodically recycled to avoid unstable states that can lead to application crashes, hangs, or memory leaks. By default, application pool recycling is overlapped, which means that the worker process that is to be shut down is kept running until after a new worker process is started. After a new worker process starts, new requests are passed to it. The old worker process shuts down after it finishes processing its existing requests, or after a configured time-out, whichever comes first. This way of recycling ensures uninterrupted service to clients. However, if an application in the application pool cannot run more than one instance of itself at a time, overlapping rotation can be disabled.
Events
| Event ID | Source | Message |
|---|---|---|
Microsoft-Windows-IIS-WMSVC |
ISAPI '%1' reported itself as unhealthy for the following reason: '%2'. | |
Microsoft-Windows-IIS-WMSVC |
ISAPI '%1' reported itself as unhealthy. No reason was given by the ISAPI. | |
Microsoft-Windows-WAS |
The Windows Process Activation Service failed to issue recycle requests to all worker processes of application pool '%1'. The data field contains the error number. | |
Microsoft-Windows-WAS |
A worker process with process id of '%1' serving application pool '%2' has requested a recycle because the worker process reached its allowed processing time limit. | |
Microsoft-Windows-WAS |
A worker process with process id of '%1' serving application pool '%2' has requested a recycle because it reached its allowed request limit. | |
Microsoft-Windows-WAS |
A worker process with process id of '%1' serving application pool '%2' has requested a recycle because it reached its scheduled recycle time. | |
Microsoft-Windows-WAS |
A worker process with process id of '%1' serving application pool '%2' has requested a recycle because it reached its virtual memory limit. | |
Microsoft-Windows-WAS |
An ISAPI reported an unhealthy condition to its worker process. Therefore, the worker process with process id of '%1' serving application pool '%2' has requested a recycle. | |
Microsoft-Windows-WAS |
An administrator has requested a recycle of all worker processes in application pool '%1'. | |
Microsoft-Windows-WAS |
The worker processes serving application pool '%1' are being recycled due to 1 or more configuration changes in the application pool properties which necessitate a restart of the processes. | |
Microsoft-Windows-WAS |
The worker processes serving application pool '%1' are being recycled due to detected problems with the IIS configuration store that may make current cached metadata invalid. | |
Microsoft-Windows-WAS |
The Windows Process Activation Service failed to overlap recycle for application pool '%1' worker process '%2'. The data field contains the error number. | |
Microsoft-Windows-WAS |
A worker process with process id of '%1' serving application pool '%2' has requested a recycle because it reached its private bytes memory limit. | |
Microsoft-Windows-WAS |
A worker process with process id of '%1' serving application pool '%2' was shutdown due to inactivity. Application Pool timeout configuration was set to %3 minutes. A new worker process will be started when needed. |