Delete all pods based on condition transition time.

pkg/kubelet/kubelet.go

@@ -75,8 +75,18 @@ const (
 	initialNodeStatusUpdateFrequency = 100 * time.Millisecond
 	nodeStatusUpdateFrequencyInc     = 500 * time.Millisecond
 
-	// Node status update frequency and retry count. Note: be cautious when changing nodeStatusUpdateFrequency,
-	// it must work with nodecontroller.nodeMonitorGracePeriod.
+	// Node status update frequency and retry count.
+	// Note: be cautious when changing the constant, it must work with nodeMonitorGracePeriod
+	// in nodecontroller. There are several constraints:
+	// 1. nodeMonitorGracePeriod must be N times more than nodeStatusUpdateFrequency, where
+	//    N means number of retries allowed for kubelet to post node status. It is pointless
+	//    to make nodeMonitorGracePeriod be less than nodeStatusUpdateFrequency, since there
+	//    will only be fresh values from Kubelet at an interval of nodeStatusUpdateFrequency.
+	// 2. nodeMonitorGracePeriod can't be too large for user experience - larger value takes
+	//    longer for user to see up-to-date node status.
+	// 3. nodeStatusUpdateFrequency needs to be large enough for Kubelet to generate node
+	//    status. Kubelet may fail to update node status reliablly if the value is too small,
+	//    as it takes time to gather all necessary node information.
 	nodeStatusUpdateFrequency = 2 * time.Second
 	nodeStatusUpdateRetry     = 5
 )
@@ -1837,20 +1847,23 @@ func (kl *Kubelet) tryUpdateNodeStatus() error {
 		node.Spec.Capacity = CapacityFromMachineInfo(info)
 	}
 
+	currentTime := util.Now()
 	newCondition := api.NodeCondition{
 		Type:          api.NodeReady,
 		Status:        api.ConditionFull,
 		Reason:        fmt.Sprintf("kubelet is posting ready status"),
-		LastProbeTime: util.Now(),
+		LastProbeTime: currentTime,
 	}
 	updated := false
 	for i := range node.Status.Conditions {
 		if node.Status.Conditions[i].Type == api.NodeReady {
+			newCondition.LastTransitionTime = node.Status.Conditions[i].LastTransitionTime
 			node.Status.Conditions[i] = newCondition
 			updated = true
 		}
 	}
 	if !updated {
+		newCondition.LastTransitionTime = currentTime
 		node.Status.Conditions = append(node.Status.Conditions, newCondition)
 	}