Issue

Jobs stay on the Build queue when there are dedicated agents with free executors.

• Note: This KB article is not applied for shared agents leased from CJOC.

Environment

• CloudBees Core on modern cloud platforms - Managed Master (CORE-MM)
• CloudBees Core on traditional platforms - Client Master (CORE-CM)
• CloudBees Jenkins Enterprise - Managed Master (CJE-MM)
• CloudBees Jenkins Team (CJT)
• CloudBees Jenkins Platform - Client Master (CJP-CM)
• Jenkins LTS

Resolution

There are multiple causes which might produce this issue, but if you want to diagnosis this issue you might want to try running in /script:

for (i in Jenkins.instance.queue.buildableItems) {
  println "considering ${i}"
  for (c in Jenkins.instance.computers) {
    println "found computer ${c}"
    EXEC: for (e in c.executors) {
      if (e.interrupted || !e.parking) continue
      println "with executor ${e}"
      def o = new Queue.JobOffer(e)
      if (!o.canTake(i)) {
        println "${o} refused ${i}"
        def node = o.node
        if (node == null) {
          println "no node associated with ${c}"
          continue
        }
        def cob = node.canTake(i)
        if (cob != null) {
          println "because of ${cob}"
          continue
        }
        for (d in hudson.model.queue.QueueTaskDispatcher.all()) {
          cob = d.canTake(node, i)
          if (cob != null) {
            println "because of ${cob} from ${d}"
            continue EXEC
          }
        }
        if (!o.available) {
          println "${o} not available"
          if (o.workUnit != null) println "has a workUnit ${o.workUnit}"
          if (c.offline) println "${c} is offline"
          if (!c.acceptingTasks) println "${c} is not accepting tasks"
        }
      }
    }
  }
}

Note: This script was proposed in JENKINS-38514

Known causes

Misconfiguration in Authorize Project

In one reported case, the root issue was that the Authorize Project plugin was configured, so Node.canTake was returning anonymous doesn’t have a permission to run on [sic]; yet the build queue (and support bundle) displayed only Waiting for next available executor.

considering hudson.model.Queue$BuildableItem:hudson.model.FreeStyleProject@1878318e[test-a]:1
found computer hudson.model.Hudson$MasterComputer@e9bc860
with executor Thread[Executor #0 for master,5,main]
JobOffer[ #0] refused hudson.model.Queue$BuildableItem:hudson.model.FreeStyleProject@1878318e[test-a]:1
because of anonymous doesn’t have a permission to run on
with executor Thread[Executor #1 for master,5,main]
JobOffer[ #1] refused hudson.model.Queue$BuildableItem:hudson.model.FreeStyleProject@1878318e[test-a]:1
because of anonymous doesn’t have a permission to run on