Memory usage of Micro Docker containers

Technical Discussion
1

I have several Payara Micro Docker services in a stack, with some services having more than one replica. Their containers are of images that extent Payara Micro’s image. It’s pretty basic:

FROM payara/micro:5.2022.5-jdk11
COPY target/*.war $DEPLOY_DIR
EXPOSE 8080 8181
CMD ["--deploymentDir", "/opt/payara/deployments", "--contextroot", "a"]

These applications do nothing more than expose a couple of REST endpoints and marshal data to/from their databases (SQL Server and/or MongoDB) - with very little data manipulation/processing/shaping:

JAX-RS Endpoint → Local EJB → Database

Without any resource restrictions in place, the containers allocate 1GB of memory!

I thought that I could drop the container memory allocation to less than 100MB, but the containers just fail due to memory requirements. I’ve settle on max 700MB with an initial of 500MB, and the containers seem to initially use a whopping 460MB of memory just idling. Keep in mind these are every small apps that do little more than basic CRUD (some are even just read only!).

  a-service:
    image: repo/services-a:1.2.3
    depends_on:
      - mongo
    ports:
      - "8081:8080"
    deploy:
      replicas: 2
    env_file: .env
    networks:
      - net
    environment:
      - MEM_MAX_RAM_PERCENTAGE=80
    deploy:
      resources:
        limits:
          cpus: '1.00'
          memory: 700M
        reservations:
          cpus: '0.50'
          memory: 500M

Here is a screenshot from Live Charts in Docker Desktop of one of the services starting up:

image
image1813×703 73.5 KB

Here is another screenshot after running a simple stress test:

for run in {1..2000}; do curl -s http://127.0.0.1:8081/a/api/v1/document/details/62fbd94e2b276e0f3d6fcc30 > /dev/null; done

image
image1813×703 75 KB

As you can see, there is an insignificant bump in memory usage (~10MB) for the entire 2000 requests.

Even at 500MB/service, this is excessive. Couple that with several services/containers, it’s prohibitive.

What can I do to reduce the memory footprint of these Payara Micro containers? Ideally, I’d like to get them down to about 50MB (or even 100MB), but any reduction at this point is welcomed.

UPDATE: added MEM_MAX_RAM_PERCENTAGE=80