let panics propagate up when processLoop panic

staging/src/k8s.io/client-go/tools/cache/controller.go

@@ -144,11 +144,11 @@ func (c *controller) Run(stopCh <-chan struct{}) {
 	c.reflectorMutex.Unlock()
 
 	var wg wait.Group
-	defer wg.Wait()
 
 	wg.StartWithChannel(stopCh, r.Run)
 
 	wait.Until(c.processLoop, time.Second, stopCh)
+	wg.Wait()
 }
 
 // Returns true once this controller has completed an initial resource listing

staging/src/k8s.io/client-go/tools/cache/controller_test.go

@@ -402,3 +402,49 @@ func TestUpdate(t *testing.T) {
 	testDoneWG.Wait()
 	close(stop)
 }
+
+func TestPanicPropagated(t *testing.T) {
+	// source simulates an apiserver object endpoint.
+	source := fcache.NewFakeControllerSource()
+
+	// Make a controller that just panic if the AddFunc is called.
+	_, controller := NewInformer(
+		source,
+		&v1.Pod{},
+		time.Millisecond*100,
+		ResourceEventHandlerFuncs{
+			AddFunc: func(obj interface{}) {
+				// Create a panic.
+				panic("Just panic.")
+			},
+		},
+	)
+
+	// Run the controller and run it until we close stop.
+	stop := make(chan struct{})
+	defer close(stop)
+
+	propagated := make(chan interface{})
+	go func() {
+		defer func() {
+			if r := recover(); r != nil {
+				propagated <- r
+			}
+		}()
+		controller.Run(stop)
+	}()
+	// Let's add a object to the source. It will trigger a panic.
+	source.Add(&v1.Pod{ObjectMeta: metav1.ObjectMeta{Name: "test"}})
+
+	// Check if the panic propagated up.
+	select {
+	case p := <-propagated:
+		if p == "Just panic." {
+			t.Logf("Test Passed")
+		} else {
+			t.Errorf("unrecognized panic in controller run: %v", p)
+		}
+	case <-time.After(wait.ForeverTestTimeout):
+		t.Errorf("timeout: the panic failed to propagate from the controller run method!")
+	}
+}