We're hosting a site on Azure as an App Service and today we had an unexpected memory behavior.
We had about 200 concurrent users (which for our application means about 3K requests/min) and it was running fine until all of a sudden the memory usage peaked. It went high for a short while but then quickly went back to previous values.
This also caused our CPU to hit 97% for a short time (a few seconds) which caused the response time to rise and also some HTTP-500-responses were sent.
We are running on one S1 instance, and we are definitely prepared to scale up/out if necessary, but we'd still like to understand more about this peak. Does anyone recognize this behavior?
I could also add that our normal memory-usage is around 60-70%, is this high? It doesn't go down even during the night when we have no users.
Additional info: Our DTU-percentage went from 25% to 50%. This is probably related. Is there a functionality to load an entire DB-table into memory if it is I/O-intensive for a short while?