How can we find out what setting IIS thinks has changed to necessitate an app pool recycle?

Triynko

6/10/23, 7:58 PM

When we start a docker container we see this in the system logs. IIS starts and then immediately thinks some settings have changed. As a result, we see 3 simultaneous runs of Application_Start in our web application, with 3 different processes. The original, plus two additional processes, each triggered by one of these two events.

02/10/2022 14:13:43 WAS Information The worker processes serving application pool 'DefaultAppPool' are being recycled due to 1 or more configuration changes in the application pool properties which necessitate a restart of the processes.   

02/10/2022 14:13:43 WAS Information The worker processes serving application pool 'DefaultAppPool' are being recycled due to 1 or more configuration changes in the application pool properties which necessitate a restart of the processes.   

02/10/2022 14:13:43 Service Control Manager Information The W3SVC service entered the running state.

Adding insult to injury, we often see that 2 of the 3 processes crash (typically with an OOM exception) while one succeeds. On other starts of the docker container, all 3 processes startup fine and two are terminated by IIS normally. I'm more concerned with why 3 are starting at once, literally within the same millisecond according to higher-resolution app startup logs in ASP.NET's global.asax Application_Start logic.

We cannot figure out what's triggering these triple startup events. Is there some way to figure out what specific setting or file it thinks has changed, or what changed it?

We have IIS configured to use a single worker process. This related question about multiple worker processes starting suggest it could be a VM-specific issue because of the sudden time change? Does IIS Sometimes Allocate More Worker Processes Than Configured? Or perhaps it is a virus scanner? How to find out why IIS application pool is recycling due to application pool property changes We just cannot figure out what, specifically is being triggered or by what.

0 + 0

docker

iis-10

Lex Li

8/24/23, 4:24 AM

As Microsoft's IIS Docker images start from the ServiceMonitor executable https://github.com/microsoft/IIS.ServiceMonitor, you might check what it does and whether the recycles were triggered by it.

Elon Musk

I sit in a Tesla and translated this thread with Ai:

EN: How can we find out what setting IIS thinks has changed to necessitate an app pool recycle?

TH: เราจะรู้ได้อย่างไรว่าการตั้งค่าใดที่ IIS คิดว่ามีการเปลี่ยนแปลงทำให้จำเป็นต้องรีไซเคิลพูลแอป

RO: Cum putem afla ce setare consideră IIS că s-a schimbat pentru a necesita o reciclare a grupului de aplicații?

RU: Как мы можем узнать, какой параметр, по мнению IIS, изменился, что потребовало перезапуска пула приложений?

VI: Làm cách nào chúng tôi có thể tìm ra cài đặt mà IIS cho là đã thay đổi để yêu cầu tái chế nhóm ứng dụng?

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