Spring Boot Playground App

This is a basic Spring Boot app which can be used to demonstrate memory consumptions. As any regular microservice app this one would contain:

• rest endpoints
• db repository
• kafka publisher/subscriber
• http client

Install

Before running the app please ensure to compile the following subprojects:

• eureka
• gateway
• microservice

You can compile them with gradle wrapper:

gradlew build

Run

Once all required jars are compiled you can launch the entire stack:

docker-compose up --build

This would start and prepare all necessary components including db, kafka, eureka, gateway, etc.

Use

After the app is launched you can use the following endpoints:

GET http://localhost:8080/microservice

GET http://localhost:8080/microservice/{id}

POST http://localhost:8080/microservice application/json {"name":"serviceA"}

Simulate Workload

After the app is launched and you have verified that endpoints work properly it might be required to simulate workload. Execute the following command to launch workload simulation:

docker-compose -f docker-compose-workload.yaml up --build

Modify RAM limits

By default the application is not limited on both docker and java heap.

1. Heap limits

Modify microservice java command in docker-compose file to add Xmx: java -Xmx100m

2. Docker limits

To set limits for microservice app container add the following to docker compose:

deploy:
  resources:
    limits:
      memory: 300M

Examine

microservice application is the one that should be examined for memory consumption.

1. Examine via VisualVM

You can check memory consumption by connecting to port 3333.

2. Examine via docker stats

Simply execute docker stats. spring-boot-playground_microservice_1 - is the container to be tracked.

3. Examine via java jcmd

Firstly you need to identify java app PID: docker exec spring-boot-playground_microservice_1 ps

and then execute for required PID: docker exec spring-boot-playground_microservice_1 jcmd 9 VM.native_memory summary