Azure App Service
Azure App Service is a service used to create and deploy scalable, mission-critical web apps.
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How to fix Azure web app with high CPU time and HTTP server errors sometimes and automatically resolved after few minutes
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Kalpesh Rajai
0
Reputation points
We have developed the web app into the .NET Blazor and running into the azure web app Linux version.
Sometime we are getting the high cpu time, high cpu percentage and http server errors.
I did not found any error or something on the application insight of the web app.
I tried to use the web app diagnostic feature but this is older then 30 days, So I can not check that traces due to the 30 days limit of the azure diagnostic data.
How can I find the cause of this issue, so we can fix it? (Till now cause is unknown.)
Azure App Service
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Alekhya Vaddepally 1,170 Reputation points Microsoft External Staff Moderator2025-04-22T18:01:19.6033333+00:00 Hi Kalpesh Rajai,
- Application Insights does not show any obvious reason, and the app service diagnostics does not help due to the 30-day retention range.
- Blazers (especially server-side blazor) may be under CPU-intelligence under the load or when large components are render. Poorly adapted loops, long -running tasks, or memory leaks can trigger CPU spikes.
- When memory uses, it can trigger waste collection and increase CPU.
- Slow-speed third-party API, database delay, or service dependence can lead to server-side timeout and errors.
- If your app is on a small app service scheme (eg B1/B2/S1), sometimes can be higher than the ability to explode traffic.
- Application Insights Profiler + Snapshot debugger Enable
- These devices give deep diagnosis during spikes, even if the logs are clear.
- Enable the profiler to automatically collect scars during high CPU use.
- Snapshot captures the state during the debugger exceptions.
- Configure auto-healing rules
- You can set auto-heels to restart a process when high CPU is detected.
phase: - Go to app service → diagnose and solve problems → Auto-Heel.
- Like determine the rules:
- Condition: CPU> 80%for 1 minute.
- Action: Recycle the process.
- Review Matrix + Alert
- Set the alert on CPU, memory and http errors. Use log to correlate issues.
- Scale up or scale out
- If load patterns show continuous spikes, consider scaling:
- From a more powerful sku (eg, from S1 to P1V2).
- Scale out by enabling the example of the example or enabling autoscale.
If the application is not catching the insight errors, add structured logging:
app.Use(async (context, next) => { var sw = Stopwatch.StartNew(); try { await next.Invoke(); } catch (Exception ex) { logger.LogError(ex, "Unhandled error: {Path}", context.Request.Path); throw; } finally { sw.Stop(); logger.LogInformation("Request {Path} took {Elapsed}ms", context.Request.Path, sw.ElapsedMilliseconds); } });https://learn.microsoft.com/en-us/azure/azure-monitor/snapshot-debugger/snapshot-debugger
https://learn.microsoft.com/en-us/azure/app-service/troubleshoot-diagnostic-logs#auto-heal
https://learn.microsoft.com/en-us/azure/app-service/monitor-app-servicehttps://learn.microsoft.com/en-us/azure/app-service/manage-scale-upif you have any further concerns or queries, please feel free to reach out to us.
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Alekhya Vaddepally 1,170 Reputation points Microsoft External Staff Moderator
2025-04-23T08:51:48.83+00:00 Hi Kalpesh Rajai,
We haven’t heard from you on the last response and was just checking back to see if you have a resolution yet. In case if you have any resolution, please do share that same with the community as it can be helpful to others. Otherwise, will respond with more details and we will try to help. -
Kalpesh Rajai 0 Reputation points
2025-04-23T09:19:35.0633333+00:00 Thank you for your comment!!
As issue is older then 30 days, So I can not check from my side,
Can Azure support team checks about it?I should try to implement your suggestions to web app, So in the future we can easily detect if something goes wrong
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Alekhya Vaddepally 1,170 Reputation points Microsoft External Staff Moderator
2025-04-23T15:32:17.9566667+00:00 Hi Kalpesh Rajai,
- You had a support plan with proactive diagnostics competent (such as premiere or Microsoft unified support), or
- You have exported external storage or log analytics work (which maintains data for a long time when configured).
- If none of these were installed, Microsoft support will not be able to achieve those specific historical logs. However, they can help you:
- Analyze any recurring patterns or issues still happening.
- Review the process usage trends (eg CPU/Memory Spikes) of the app.
- Help you optimize configuration and scaling.
- Help in installing proactive alerts, autoscaling or auto-healing rules.
- If you want to attach them, I recommend increasing a support request with the category "App Service - Performance Issues" category and include screenshots (such as you shared), as well as the approximate date/time of the event.
- you can also Implement Proactive Monitoring Now:
- You are completely on the right track saying that you want to apply monitoring and diagnosis now, so the next time there is an issue:
- It is automatically detected.
- You have logs, scars and matrix that are ready for examination.
- You can work immediately or auto-richer.
- Application insight profiler
- Snapshot
- Auto-heel rules
- Autoscale settings
- Export logs for long -term retention to log analytics (if configured if configured).
https://learn.microsoft.com/en-us/azure/azure-portal/supportability/how-to-create-azure-support-request
https://learn.microsoft.com/en-us/previous-versions/azure/azure-monitor/app/export-telemetry
if you have any further concerns or queries, please feel free to reach out to us.
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Alekhya Vaddepally 1,170 Reputation points Microsoft External Staff Moderator
2025-04-24T10:27:05.44+00:00 Hi Kalpesh Rajai, We haven’t heard from you on the last response and was just checking back to see if you have a resolution yet. In case if you have any resolution, please do share that same with the community as it can be helpful to others. Otherwise, will respond with more details and we will try to help.
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