We have a jenkins environment where we have a single server with multiple executors (4). Sometimes the display has multiple idles, even though all executors are in use:
Jenkins pipeline idle lightweight executor list is growing
Jenkins master zombie executors
Followup - Investigate root cause of idle executors
Pipelines leak OneOffExecutors when triggered on a temporary offline master
I am seeing the same issue in Jenkins version 2.190.1 We are running one master and all our builds are pipeline builds.
https://github.com/jenkinsci/jenkins/pull/4329 likely fixes it
Assigned to me to keep track of it and added the lts-candidate as the PR seems to fix a bunch of tickets.
See also: JENKINS-60348
Released in 2.208