I'm having an issue where on a single app service plan there are multiple sites with the same application. This application has a somewhat heavy initialization.
The issue is that on scale out, the initialization is run for all sites at once, and sites are brought onto the new instance is their initialization completes. This means that some sites may be directed to the new instance while initialization of other sites is not complete, sending the user to a server under high load.
Does anyone have a good solution for this? Right now I'm thinking I may have to use a separate plan for each site.