Merge pull request kubernetes#120980 from p0lyn0mial/upstream-client-go-close-watcher

reflector: close an established watcher when the StopCh was closed

Author: k8s-ci-robot

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

@@ -397,6 +397,11 @@ func (r *Reflector) watch(w watch.Interface, stopCh <-chan struct{}, resyncerrc
 		// give the stopCh a chance to stop the loop, even in case of continue statements further down on errors
 		select {
 		case <-stopCh:
+			// we can only end up here when the stopCh
+			// was closed after a successful watchlist or list request
+			if w != nil {
+				w.Stop()
+			}
 			return nil
 		default:
 		}

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

@@ -28,6 +28,8 @@ import (
 	"testing"
 	"time"
 
+	"github.com/stretchr/testify/require"
+
 	v1 "k8s.io/api/core/v1"
 	apierrors "k8s.io/apimachinery/pkg/api/errors"
 	"k8s.io/apimachinery/pkg/api/meta"
@@ -124,6 +126,26 @@ func TestReflectorResyncChan(t *testing.T) {
 	}
 }
 
+// TestEstablishedWatchStoppedAfterStopCh ensures that
+// an established watch will be closed right after
+// the StopCh was also closed.
+func TestEstablishedWatchStoppedAfterStopCh(t *testing.T) {
+	ctx, ctxCancel := context.WithCancel(context.TODO())
+	ctxCancel()
+	w := watch.NewFake()
+	require.False(t, w.IsStopped())
+
+	// w is stopped when the stopCh is closed
+	target := NewReflector(nil, &v1.Pod{}, nil, 0)
+	err := target.watch(w, ctx.Done(), nil)
+	require.NoError(t, err)
+	require.True(t, w.IsStopped())
+
+	// noop when the w is nil and the ctx is closed
+	err = target.watch(nil, ctx.Done(), nil)
+	require.NoError(t, err)
+}
+
 func BenchmarkReflectorResyncChanMany(b *testing.B) {
 	s := NewStore(MetaNamespaceKeyFunc)
 	g := NewReflector(&testLW{}, &v1.Pod{}, s, 25*time.Millisecond)