Azure App Service - Memory Consumption

Question

Azure App Service - Memory Consumption

_Julien Jalageas.AZ 21

Hi,

I am in the process of migrating on-prem Tomcat Java webapps to Azure App Services. Currently, we have 30 web applications running on a tomcat with 6GB of allocated memory (4GB heap, 2GB permgen). However, we have deployed only 9 webapps on azure, each to their own Linux app service, all part of the same app service plan with Basic B3 pricing tier and 7GB of memory, and the memory usage is at 100% which has forced us to stop certain app services in order to test other ones. All 9 App Services have a Java 8 and Apache Tomcat 8.5 runstack.

Are app services more memory intensive than a traditional webapp? Does the app service plan require more memory than a traditional Tomcat server to run the same number of applications?

Thanks,

Julien Jalageas

Grmacjon-MSFT 19,151 Reputation points Moderator

2023-02-06T19:41:00.2966667+00:00

Hi @_Julien Jalageas.AZ checking in to see if the below response helped answer your question. Let us know if you have any more questions.
Khurram Rahim 1,851 Reputation points Volunteer Moderator

2023-02-06T20:39:47.8366667+00:00

It's possible that Azure App Services are more memory-intensive than a traditional webapp running on a standalone Tomcat server, as the platform provides additional features and services (such as automatic scaling and load balancing) that consume some memory. However, the root cause of the high memory usage in your case may also be due to other factors, such as inefficient coding or memory leaks in your web applications, or an insufficient Java heap size configuration.

As for the required memory, the actual amount of memory needed depends on the nature and size of your web applications, as well as the number of concurrent users and their usage patterns. It's not possible to make a blanket statement about whether App Services require more memory than a standalone Tomcat server, as it depends on the specifics of your deployment. You may want to consider monitoring the memory usage of your App Services over time, and adjust the heap size and other configurations as needed to optimize performance.
Jalageas, Julien E 0 Reputation points

2023-02-07T16:23:09.4233333+00:00

@Khurram Rahim As of now, there is very limited usage of these applications since this is a DEV environment. Applications run with no performance issue on a Tomcat server, and memory usage seems to be around 400mb per app when run in my local environment. I've found that the app service's memory usage is around 2gb regardless of the size of the application that is deployed. This however only occurs for applications deployed as WAR files on a tomcat run stack app service. If I deploy as a JAR with a standard java run stack, the memory usage is considerably lower.

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Your answer

Grmacjon-MSFT 19,151 Reputation points Moderator

2023-02-06T19:41:00.2966667+00:00

Hi @_Julien Jalageas.AZ checking in to see if the below response helped answer your question. Let us know if you have any more questions.
Khurram Rahim 1,851 Reputation points Volunteer Moderator

2023-02-06T20:39:47.8366667+00:00

It's possible that Azure App Services are more memory-intensive than a traditional webapp running on a standalone Tomcat server, as the platform provides additional features and services (such as automatic scaling and load balancing) that consume some memory. However, the root cause of the high memory usage in your case may also be due to other factors, such as inefficient coding or memory leaks in your web applications, or an insufficient Java heap size configuration.

As for the required memory, the actual amount of memory needed depends on the nature and size of your web applications, as well as the number of concurrent users and their usage patterns. It's not possible to make a blanket statement about whether App Services require more memory than a standalone Tomcat server, as it depends on the specifics of your deployment. You may want to consider monitoring the memory usage of your App Services over time, and adjust the heap size and other configurations as needed to optimize performance.
Jalageas, Julien E 0 Reputation points

2023-02-07T16:23:09.4233333+00:00

@Khurram Rahim As of now, there is very limited usage of these applications since this is a DEV environment. Applications run with no performance issue on a Tomcat server, and memory usage seems to be around 400mb per app when run in my local environment. I've found that the app service's memory usage is around 2gb regardless of the size of the application that is deployed. This however only occurs for applications deployed as WAR files on a tomcat run stack app service. If I deploy as a JAR with a standard java run stack, the memory usage is considerably lower.

Answer 1

Grmacjon-MSFT 19,151 Moderator

Hi @_Julien Jalageas.AZ ,

Apologies for the delay in response.

Yes, App Service plans are more memory-intensive than traditional web applications because they are designed to support multiple applications and provide high availability and scalability.

App Service plans are designed to provide a scalable and reliable hosting environment for your web applications. The amount of memory required for your web applications will depend on the specific requirements of your applications and the workloads they are handling.

The Basic B3 pricing tier provides 7GB of memory, which should be sufficient for running 9 web applications. However, if your applications have high memory usage or are experiencing heavy workloads, you may need to increase the memory allocation or upgrade to a higher pricing tier to support your applications.

You can monitor the memory usage of your App Service plan Azure Monitor and autoscale individual web applications by enabling autoscaling by following the steps here: Get Started with Autoscale in Azure. Autoscale is a service that allows you to automatically add and remove resources according to the load on your application.

Hope that helps. Please let us know if you have further questions.

Thanks,

Grace

Jalageas, Julien E 0 Reputation points

2023-02-07T16:17:09.8766667+00:00

Thanks Grace, the web app is a Spring Boot Java application, when I run it in eclipse, it seems to use about 400mb in memory, whereas it uses 2GB when deployed as an app service. This is why I am trying to understand if an app service on its own uses more memory than a war file deployed on a application server.

Those 9 applications are mature so code issue or memory leak is unlikely, as I said, there is no performance issue when deployed on a tomcat server.

This, however only occurs for applications deployed as WAR files on a tomcat run stack app service. If I deploy as a JAR with a standard java run stack, the memory usage is considerably lower. As of now, it is not possible to build every application as a JAR.

Since this is a migration effort, the problem becomes how much memory will be needed to handle 30 Java applications? 60gb? That doesn't sound right.
_Julien Jalageas.AZ 21 Reputation points

2023-06-15T23:27:24.2133333+00:00

As of now, there is very limited usage of these applications since this is a DEV environment. Applications run with no performance issue on a Tomcat server, and memory usage seems to be around 400mb per app when running in my local environment. I've found that the app service's memory usage is around 2gb regardless of the size of the application that is deployed. This however only occurs for applications deployed as WAR files on a tomcat run stack app service. If I deploy as a JAR with a standard java run stack, the memory usage is considerably lower. We are migrating 30 Java web applications, are App Services a good match?
Grmacjon-MSFT 19,151 Reputation points Moderator

2023-07-06T23:06:02.2033333+00:00

Hi @_Julien Jalageas.AZ , thanks for the additional information & questions.

How many apps do you have in your App Service Plan (ASP)? Are all 30 apps going to be in one ASP?

If you are asking whether Azure App Service will be able to host all your java applications then the answer is yes but it depends on how you create your app service architecture.

Azure App service offers 6 pricing tiers for hosting your web applications. The pricing tier of an App Service plan determines what App Service features you get and how much you pay for the plan. The Basic, Standard, Premium, PremiumV2, and PremiumV3 tiers run apps on dedicated Azure VMs. Keep in mind that only apps in the same App Service plan share the same compute resources. The higher the tier, the more VM instances are available to you for scale-out. For the basic and higher tiers on app services, you can technically run unlimited apps however there is still a finite amount of CPU and memory available to your ASP.

You might want to explore S1 tier or higher based on some of the requirements you've shared. You could create two ASP, one for your applications that are deployed as WAR files and the other ASP for apps deployed as a JAR. You can also group your apps based on other factors like size, high/low traffic, memory usage, CPU consumption, etc.

(Please note that there are a lot of variables that come into play regarding apps per instance. As a result, Microsoft does not offer a formal recommendation. Your experiences will be unique to others. As I mentioned earlier you can scale up/down and in/out in minutes if your apps need additional resources at any time)

Overall, App Services is be a good match for your Java web applications, but the memory requirements will depend on a number of factors. With the scalability and flexibility of App Services, you should be able to adjust your resources as needed to ensure that your applications are running smoothly.

Hope that helps. please le me know if you have further questions.

Best,

Grace

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Azure App Service - Memory Consumption

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