My website is very slow to start up

Mark Evans 5

I have a simple Blazor server app connected to free Azure SQL. It works fine but if nobody uses it for a while then it is very, very slow to start. To try and fix this I upgraded to the plan B1 and enabled "Always On". I don't believe this is a problem with my code because I created a simple HTML page with absolutely no code and that is also very slow to start. It takes 20 seconds to load and returns no content. I need to refresh it several times before my simple text content is returned. I believe that Microsoft is shutting down my app despite the "Always On" setting. This is disappointing because I want to use Azure but this is unacceptable. This is a test site. I don't need to pay the considerable cost for a production subscription. But my clients need to view this test site without these issues.

Vlad Costa 1,480 Reputation points

2024-05-17T08:05:04.73+00:00
The issue you're experiencing is known as a "cold start". This happens when an application hasn't been used for a while and must be loaded into memory before responding to requests. Even with the "Always On" setting enabled, your app can still experience cold starts.

Here are a few suggestions to improve the startup time of your app:

Optimise Your App: Try to keep the size of your resources small. Only add the absolutely required dependencies. This can help reduce the time it takes to load your app into memory.

Split Your App: If your app is large, consider splitting it into different-function apps scaled independently. This can help reduce the size of each individual app and improve startup time.

Upgrade Your Plan: While you mentioned that you're currently on the B1 plan, you might want to consider upgrading to a higher tier. Higher tiers offer better performance and may help reduce cold start times.

Use Azure Functions Premium Plan: The Azure Functions Premium plan offers pre-warmed instances, which can help reduce cold start times.

Remember, even with these optimizations, cold starts can still occur, especially if your app hasn't been used for a while. It's a common challenge in serverless architectures.

https://azure.microsoft.com/en-us/blog/understanding-serverless-cold-start/
Vlad Costa 1,480 Reputation points

2024-05-17T08:07:50.76+00:00
The issue you're experiencing is known as a "cold start". This happens when an application hasn't been used for a while and must be loaded into memory before responding to requests. Even with the "Always On" setting enabled, your app can still experience cold starts.

Here are a few suggestions to improve the startup time of your app:

Optimise Your App: Try to keep the size of your resources small. Only add the absolutely required dependencies. This can help reduce the time it takes to load your app into memory.

Split Your App: If your app is large, consider splitting it into different-function apps scaled independently. This can help reduce the size of each individual app and improve startup time².

Upgrade Your Plan: While you mentioned that you're currently on the B1 plan, you might want to consider upgrading to a higher tier. Higher tiers offer better performance and may help reduce cold start times.

Use Azure Functions Premium Plan: The Azure Functions Premium plan offers pre-warmed instances, which can help reduce cold start times.

Remember, even with these optimizations, cold starts can still occur, especially if your app hasn't been used for a while. It's a common challenge in serverless architectures

https://azure.microsoft.com/en-us/blog/understanding-serverless-cold-start/
VenkateshDodda-MSFT 22,636 Reputation points Microsoft Employee

2024-05-22T07:42:28.06+00:00

@Mark Evans Thanks for posting your question in Microsoft Q&A, apologize for any inconvenience caused on this.

Adding to Vlad Costa you can follow this troubleshooting steps to troubleshoot performance issues in app service.

Hope this helps let me know if you have any questions or if you are still facing the issue.
Mark Evans 5 Reputation points

2024-05-22T10:44:18.0033333+00:00

I guess I was naive to think that I would get any help here. How do you suggest I optimize a page that is a simple test HTML file with one line of text in it? I wanted to use Azure but it seem that I will have to look elsewhere.
VenkateshDodda-MSFT 22,636 Reputation points Microsoft Employee

2024-05-22T12:15:48.2333333+00:00

@Mark Evans Thanks for your response.

I do understand your concern, that is the reason I have mentioned before to follow the documentation steps to know the performance issue why your webapp is taking 20 sec when you have already setup the Always on feature.

In case, If you couldn't find the root cause or action plan to resolve the issue I will suggest you to engage us over 1:1 support request. So, we can review the backend logs.

In case if you don't have a support plan then please refer to my private comment.

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