Last time I tried docker compose, elastic take a lot of RAM !!
You need to limit its RAM usage with mem_limit :

[...]
  elasticsearch:
    networks:
      - backend
    container_name: clearml-elastic
    mem_limit: 2g
    environment:
      bootstrap.memory_lock: "true"
      cluster.name: clearml
[...]

And how much memory does ElasticSearch realistically need?

@<1576381444509405184:profile|ManiacalLizard2> Do you have an observation/experience as to what happens when ES hits the limit?

Thank you for getting back!
I have reduced it to a max of 2GB for the container and 1GB for the java heap inside the container. Up to now I haven’t experienced any issues 👍

Sorry I missed your message: no I don't know what happen when ES reach its RAM limit. We do self-host in Azure and use ES SaaS. Our cloud engineer manage that part.
My only experience was when I tried to spin up my local server, from docker compose, to test something and it took my PC down because ES eat all my RAM !!

I think ES use a greedy strategy where it allocate first then use it from there ...

Can you share the elastic part of your docker container? Are you using any overrides?

@<1576381444509405184:profile|ManiacalLizard2> what happens when ES hits the limit? Does it go OOM, or does the scalars loading just take a long time in the web-ui? And what about tasks putting scalars in the index?

It seems elastic has allocated a heap of 32GiB, but uses only 4GiB. Where/why have 32GiB been allocated?