Increased usage of 0-executor master (flyweight visibility?)

[Gavin Davies]

Hello,

We have a Jenkins running Jenkins LTS 2.222.4 on Kuberentes via the Jenkins helm chart. We use Kubernetes agents on an EC2 autoscaling group. We have 2216 projects, each of which uses Jenkinsfile.Master is set to 0 executors and no builds should execute there (except for branch indexing and the flyweight executors dealing with Groovy etc). 

Since Friday 24th July, we have started to see FAR more activity on master and Jenkins CPU usage increased.

When a job is executing, we now see it listed on the agent that it is running on AND often under master as well. Clicking on the job’s log shows ‘running on’ referencing the agent, NOT master. Before Friday, we were not seeing any jobs listed under master except for during branch indexing or the initial pre-checkout phase.

We would like to know if anything has changed on Jenkins, whereby flyweight executors are shown under master? We don’t think we changed anything at our end before this happened.

Should the flyweight executors be showing up under master in this way? Or, have we totally misread the situation? 

Thanks,

- Gavin