PLEG is not healthy: healthy() code part

pleg_unhealthy_healthy_code_part.md

//// pkg/kubelet/pleg/generic.go - Healthy()

// The threshold needs to be greater than the relisting period + the
// relisting time, which can vary significantly. Set a conservative
// threshold to avoid flipping between healthy and unhealthy.
relistThreshold = 3 * time.Minute
:
func (g *GenericPLEG) Healthy() (bool, error) {
  relistTime := g.getRelistTime()
  elapsed := g.clock.Since(relistTime)
  if elapsed > relistThreshold {
    return false, fmt.Errorf("pleg was last seen active %v ago; threshold is %v", elapsed, relistThreshold)
  }
  return true, nil
}

//// pkg/kubelet/kubelet.go - NewMainKubelet()
func NewMainKubelet(kubeCfg *kubeletconfiginternal.KubeletConfiguration, ...
:
  klet.runtimeState.addHealthCheck("PLEG", klet.pleg.Healthy)

//// pkg/kubelet/kubelet.go - syncLoop()
func (kl *Kubelet) syncLoop(updates <-chan kubetypes.PodUpdate, handler SyncHandler) {
:
// The resyncTicker wakes up kubelet to checks if there are any pod workers
// that need to be sync'd. A one-second period is sufficient because the
// sync interval is defaulted to 10s.
:
  const (
    base   = 100 * time.Millisecond
    max    = 5 * time.Second
    factor = 2
  )
  duration := base
  for {
	  if rs := kl.runtimeState.runtimeErrors(); len(rs) != 0 {
		  glog.Infof("skipping pod synchronization - %v", rs)
		  // exponential backoff
		  time.Sleep(duration)
		  duration = time.Duration(math.Min(float64(max), factor*float64(duration)))
		  continue
	  }
    :
  }
:
}

//// pkg/kubelet/runtime.go - runtimeErrors()
func (s *runtimeState) runtimeErrors() []string {
:
	for _, hc := range s.healthChecks {
		if ok, err := hc.fn(); !ok {
			ret = append(ret, fmt.Sprintf("%s is not healthy: %v", hc.name, err))
		}
	}
:
}