High CPU uitlization on window app service plan

Question

High CPU uitlization on window app service plan

Kuldeep Singh(OT) 75

Hi Team,

In my window app service plan i get daily alert of cpu utilization on 3:15 PM aggregator is max.

if i check manually the plan metrices for this time, cpu max is over 80 and avg is near 30.

We have total 15 app in this plan. and one is functions app.

i have check cpu metices for all app in this time interval, nothing unusal or high cpu utilization showing.

in function app am not seeing any function to be exceuted at that time, last function executed on 3:00 PM.

can you suggest more to resolve this error.

Kuldeep Singh(OT) 75 Reputation points

2024-06-09T09:58:39.5+00:00

can anyone pls support on this
SnehaAgrawal-MSFT 22,686 Reputation points Moderator

2024-06-11T07:52:39.91+00:00
@Kuldeep Singh(OT) Thanks for asking question!

If you are high CPU for Azure windows Apps you can follow below steps to troubleshoot.

Open a browser to the Azure Portal

Navigate to one of your web apps

On the left navigation bar, click the Diagnose and Solve Problems tab

Select Availability and Performance section on the portal.

Click on the High CPU Analysis.

Review your App Service Plan Density. This check will ensure the App Service Plan is not over the safe limit or overstuffed due to many apps in the service plan. As you mentioned you have 15 app in your App Service plan.

Based on your above description, there are two scenarios where high CPU usage may be observed, particularly in small instances:

(1) The plan has a high site density

Since sites within the same plan share the same set of machines, each site has a set of system processes running alongside it. As the number of sites increases within a plan, the count of these system processes also increases. This can lead to a larger number of processes competing for resources, such as kernel mode CPU.

To ensure optimal performance and resource allocation, it is recommended to maintain a reasonable number of sites within each plan. Below is the best practice site count we can follow:

Further best practices to tackle high CPU issues in Azure App Service mentioned in this blog provides a comprehensive guide on how to monitor and address high CPU usage.

https://techcommunity.microsoft.com/t5/apps-on-azure-blog/azure-app-service-limit-4-cpu-windows/ba-p/3899579

https://azure.github.io/AppService/2020/10/05/Diagnose-App-with-High-CPU.html

Hope this helps, please let us know if issue remains, happy to assist you further.
Kuldeep Singh(OT) 75 Reputation points

2024-06-12T07:08:40.24+00:00

Thanks for your answer but its not helping to find the which resources cosuming high memory at that point fo time
SnehaAgrawal-MSFT 22,686 Reputation points Moderator

2024-06-17T05:50:18.7366667+00:00

Reached out to you Privately.
Kuldeep Singh(OT) 75 Reputation points

2024-06-17T10:41:04.0933333+00:00

HI i have shared the reuired details, pls validate
SnehaAgrawal-MSFT 22,686 Reputation points Moderator

2024-06-24T11:59:01.27+00:00

Working privately.

1 answer

Your answer

Kuldeep Singh(OT) 75 Reputation points

2024-06-09T09:58:39.5+00:00

can anyone pls support on this
SnehaAgrawal-MSFT 22,686 Reputation points Moderator

2024-06-11T07:52:39.91+00:00

@Kuldeep Singh(OT) Thanks for asking question!

If you are high CPU for Azure windows Apps you can follow below steps to troubleshoot.

Open a browser to the Azure Portal

Navigate to one of your web apps

On the left navigation bar, click the Diagnose and Solve Problems tab

Select Availability and Performance section on the portal.

Click on the High CPU Analysis.

Review your App Service Plan Density. This check will ensure the App Service Plan is not over the safe limit or overstuffed due to many apps in the service plan. As you mentioned you have 15 app in your App Service plan.

Based on your above description, there are two scenarios where high CPU usage may be observed, particularly in small instances:

(1) The plan has a high site density

Since sites within the same plan share the same set of machines, each site has a set of system processes running alongside it. As the number of sites increases within a plan, the count of these system processes also increases. This can lead to a larger number of processes competing for resources, such as kernel mode CPU.

To ensure optimal performance and resource allocation, it is recommended to maintain a reasonable number of sites within each plan. Below is the best practice site count we can follow:

Further best practices to tackle high CPU issues in Azure App Service mentioned in this blog provides a comprehensive guide on how to monitor and address high CPU usage.

https://techcommunity.microsoft.com/t5/apps-on-azure-blog/azure-app-service-limit-4-cpu-windows/ba-p/3899579

https://azure.github.io/AppService/2020/10/05/Diagnose-App-with-High-CPU.html

Hope this helps, please let us know if issue remains, happy to assist you further.
Kuldeep Singh(OT) 75 Reputation points

2024-06-12T07:08:40.24+00:00

Thanks for your answer but its not helping to find the which resources cosuming high memory at that point fo time
SnehaAgrawal-MSFT 22,686 Reputation points Moderator

2024-06-17T05:50:18.7366667+00:00

Reached out to you Privately.
Kuldeep Singh(OT) 75 Reputation points

2024-06-17T10:41:04.0933333+00:00

HI i have shared the reuired details, pls validate
SnehaAgrawal-MSFT 22,686 Reputation points Moderator

2024-06-24T11:59:01.27+00:00

Working privately.

Answer 1

kuldeep Singh 25

Closing comment -

There is a glich in Window app service plan which make app service plan spike in 24 hrs at regular interval but its come for short life time. So, you will not be able to dianose which app service is creating this issue.

when you raise case with tech, they will also not able to find the issue and they just recommend to move monitor the avg aggregation instead of max aggregation,

Microsoft product team shoud look into this and must resolve it.

Thanks

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High CPU uitlization on window app service plan

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