Send a pod event if preStop hook did not finish in time.

pkg/kubelet/dockertools/docker_manager.go

@@ -1529,6 +1529,8 @@ func (dm *DockerManager) killContainer(containerID kubecontainer.ContainerID, co
 		select {
 		case <-time.After(time.Duration(gracePeriod) * time.Second):
 			glog.Warningf("preStop hook for container %q did not complete in %d seconds", name, gracePeriod)
+			message := fmt.Sprintf("preStop hook for container %q did not complete in %d seconds", name, gracePeriod)
+			dm.generateFailedContainerEvent(containerID, pod.Name, events.UnfinishedPreStopHook, message)
 		case <-done:
 			glog.V(4).Infof("preStop hook for container %q completed", name)
 		}

pkg/kubelet/events/event.go

@@ -74,4 +74,5 @@ const (
 	// Lifecycle hooks
 	FailedPostStartHook   = "FailedPostStartHook"
 	FailedPreStopHook     = "FailedPreStopHook"
+	UnfinishedPreStopHook = "UnfinishedPreStopHook"
 )