Azure: What does recycling of Azure App Service app mean?

Question

I tried to find an answer to this simple question. Is it synonymous to restarting the app?

Answer 1

@Jandos , Thanks for the question.

Short Answer: No, recycling is not the same as the restart.

Long Answer:

Web App Restart that goes out and fires restart across all instances at the same time. (If you have single instance then the impact is the same).

Similar to IIS concept, as App Service behind the scene runs on IIS. App Service supports a variety of development frameworks, including ASP.NET, classic ASP, node.js, PHP, and Python - all of which run as extensions within IIS.

-Worker process recycling is the replacing of the instance of the application in memory. Can automatically recycle worker processes by restarting the worker process, or worker processes, that are assigned to an application pool. This helps keep problematic applications running smoothly, and minimizes problems such as memory leaks.
On App Servvice - Apps run inside of low-privileged worker processes using a random application pool identity.
Application code has access to the memory space associated with the worker process, as well as any child processes that may be spawned by CGI processes or other applications.

Furthermore, if you have an application pool with applications that depend on state data, you must decide whether or not to recycle the worker processes that are assigned to that application pool. When you recycle a worker process, the state data for applications that is maintained in process is lost. In this case, do not use recycling.

Kindly see these docs for more information on this:

Operating system functionality on Azure App Service

Auto Healing Experience in App Service Diagnostics

Azure App Service Web App troubleshooting blade and tools -You may also checkout Recycle and Reboot insights from App Service diagnostics.

Please let us know if this helps or you have more questions on this topic, we will happy to follow-up further.
I'll also share your feedback with our content team to highlight more on this topic in the Azure docs, as required.