Sitecore shutting down exception - cache are cleared

Question

We are getting this exception frequently on both CM and CD that Sitecore is shutting down and Prefetch and other cache are getting cleared.

Sitecore Prefetch master cache max size is 200 MB and when it was cleared its running cache size was 175MB (less than the max cache size). What can be the reasons for this and how can I resolve this?

Is sitecore shut down is only due to this cache clear or there could be other reasons?

Sitecore version - 9.1

Answer 1

If your Sitecore instance is built around Microsoft Azure cloud services (PaaS), you can check the CPU utilization in Azure. There are two ways to check the CPU utilization of a web app in Azure:

App Service Plan -> Overview -> CPU Percentage chart (overall CPU utilization of the resource in the app service plan). Go to the specific Azure resource, such as a web app, and then click on "Diagnose and solve problems" -> "Availability and Performance" -> "CPU Usage". I would also suggest checking Sitecore to prevent long-running processes and any custom code that may cause this issue.

Answer 2

As per the screenshot, it shows primary reason is insufficient memory. Sitecore can shut down if the memory available memory is not sufficient and the worker process may crash. One can add more memory to solve this issue or do code refactoring for other memory issues. Also, try this solution KeepAlive

Other reasons could be:

1. Unhandle Exception.
2. Any write to application bin directory.
3. Any change to web.config.
4. Anti-virus program that touch files.
5. One of ProcessModel attribute in machine.config that cause application recycling.

Hope it helps!

Answer 3

There may be one or more reasons, due to which your Sitecore CM/CD Servers crash. You can verify the followings.

1. Hosting environment initiated shutdown: This falls in the category of Soft Crash category and you will be able to see this error message in your Sitecore log file.
   • Check Application Pool settings
   • Check ASP.NET worker process restart reasons
2. OutOfMemoryException – This falls in Hard Crash category, where your Sitecore instance will restart abruptly and when you open the Sitecore log files, it will show you lots of OutOfMemoryException errors.
   • Check caching configurations
   • Check IIS is running in X64 Mode
   • Get Crash Dump and analyze it
3. Check Memory usage: If you see the Memory is always under pressure — Either it can be memory leak OR Order a RAM.

For details explanation of all of the above things, you can refer to the this.

Answer 4

The log message does not definitively indicate that the cache clearing was related to the application shutting down. The shutdown was nearly 2 minutes after the cache clear. Caches will often get cleared as a normal part of Sitecore operations - tuning them is important for overall system performance, but cache clearing is expected as websites may run for weeks at a time without shutting down.

Do you have any metrics to see what the memory utilization was by the system? Is your Sitecore instance hosted on premises, or on Azure / another cloud service? Depending on where your application is hosted, you have different data available to try and understand why the app restarted.