Merge pull request #29550 from caesarxuchao/fix-28713

Automatic merge from submit-queue

[Garbage Collector] GC waits for all reflectors to be synced before starting workers

Fix 28713. See https://github.com/kubernetes/kubernetes/issues/28713#issuecomment-234826276 for details on the cause of the flake. The test has passed 100 times locally.

pkg/controller/garbagecollector/garbagecollector.go

@@ -685,10 +685,22 @@ func (gc *GarbageCollector) processItem(item *node) error {
 }
 
 func (gc *GarbageCollector) Run(workers int, stopCh <-chan struct{}) {
+	glog.Infof("Garbage Collector: Initializing")
 	for _, monitor := range gc.monitors {
 		go monitor.controller.Run(stopCh)
 	}
 
+	wait.PollInfinite(10*time.Second, func() (bool, error) {
+		for _, monitor := range gc.monitors {
+			if !monitor.controller.HasSynced() {
+				glog.Infof("Garbage Collector: Waiting for resource monitors to be synced...")
+				return false, nil
+			}
+		}
+		return true, nil
+	})
+	glog.Infof("Garbage Collector: All monitored resources synced. Proceeding to collect garbage")
+
 	// worker
 	go wait.Until(gc.propagator.processEvent, 0, stopCh)
 
@@ -697,7 +709,7 @@ func (gc *GarbageCollector) Run(workers int, stopCh <-chan struct{}) {
 		go wait.Until(gc.orphanFinalizer, 0, stopCh)
 	}
 	<-stopCh
-	glog.Infof("Shutting down garbage collector")
+	glog.Infof("Garbage Collector: Shutting down")
 	gc.dirtyQueue.ShutDown()
 	gc.orphanQueue.ShutDown()
 	gc.propagator.eventQueue.ShutDown()