First Request After a While Takes Seconds to Return

Question

I have a Function App running under Dedicated App Service plan. This app has many types of functions which interacts with Azure Table Storage, Blob Storage. Among these functions, there is a HTTP triggered function that makes a call to Azure Table Storage, receives the response, publishes an event using IAsyncCollector of EventHub and returns a response. Lately I have been observing that if no calls have been made to this function for a while, then the first request response takes a while like 10 seconds to over a minute.

During the investigation to find the cause of this issue, I have found that the Azure Table Storage is causing a lot of delays. One particular HTTP call that I found was causing the delay is Azure Table Storage's CreateIfNotExistsAsync which makes an HTTP call to create a table and returns 409 if table already exists. Is this normal? Should table creation logic be called in ASP.NET Core's Startup file?

Answer 1

hi, if you are sure that performance bottleneck comes from CreateIfNotExistsAsync then yes you may try to move it to app startup or to installation script which will create table during installation. In this case you won't need to call it on each http request.
Also try sync version (CreateIfNotExists) - we used it and in our case it didn't case noticable performance problems.