You’re getting rate limited which is a safety feature to avoid crashing the hub, see the config docs:
I would like to know how many concurrent requests JupyterHub can support.
There are a lot of variables here so there isn’t any one right answer. It depends on your setup (are you using zero-to-jupyterhub-k8s with kubespawner?), the image and resource limits you’ve put in place, if you’re pre-pulling images on the user nodes, if you’re pre-scaling user node capacity with placeholders:
Etc. There have been several threads related to this topic and my team has developed some open source tooling that we use to stress test our deployments:
You might find that useful for your testing. If nothing else you can at least refer to the other previous forum threads linked here: