Move reset watches critical section inside of startEventSources.

Author: godwinpang

pkg/internal/controller/controller.go

@@ -233,12 +233,6 @@ func (c *Controller[request]) Start(ctx context.Context) error {
 
 		c.LogConstructor(nil).Info("Starting Controller")
 
-		// All the watches have been started, we can reset the local slice.
-		//
-		// We should never hold watches more than necessary, each watch source can hold a backing cache,
-		// which won't be garbage collected if we hold a reference to it.
-		c.startWatches = nil
-
 		// Launch workers to process resources
 		c.LogConstructor(nil).Info("Starting workers", "worker count", c.MaxConcurrentReconciles)
 		wg.Add(c.MaxConcurrentReconciles)
@@ -325,6 +319,12 @@ func (c *Controller[request]) startEventSources(ctx context.Context) error {
 			})
 		}
 		retErr = errGroup.Wait()
+
+		// All the watches have been started, we can reset the local slice.
+		//
+		// We should never hold watches more than necessary, each watch source can hold a backing cache,
+		// which won't be garbage collected if we hold a reference to it.
+		c.startWatches = nil
 	})
 
 	return retErr

pkg/internal/controller/controller_test.go

@@ -503,7 +503,7 @@ var _ = Describe("controller", func() {
 			Expect(err.Error()).To(ContainSubstring("timed out waiting for source"))
 		})
 
-		It("should only start sources once when called multiple times", func() {
+		It("should only start sources once when called multiple times concurrently", func() {
 			ctx, cancel := context.WithCancel(context.Background())
 			defer cancel()
 
@@ -532,6 +532,23 @@ var _ = Describe("controller", func() {
 			wg.Wait()
 			Expect(startCount.Load()).To(Equal(int32(1)), "Source should only be started once even when called multiple times")
 		})
+
+		It("should reset c.startWatches to nil after returning", func() {
+			ctx, cancel := context.WithCancel(context.Background())
+			defer cancel()
+
+			ctrl.CacheSyncTimeout = 1 * time.Millisecond
+
+			src := source.Func(func(ctx context.Context, _ workqueue.TypedRateLimitingInterface[reconcile.Request]) error {
+				return nil
+			})
+
+			ctrl.startWatches = []source.TypedSource[reconcile.Request]{src}
+
+			err := ctrl.startEventSources(ctx)
+			Expect(err).NotTo(HaveOccurred())
+			Expect(ctrl.startWatches).To(BeNil(), "startWatches should be reset to nil after returning")
+		})
 	})
 
 	Describe("Processing queue items from a Controller", func() {