🐛 Controller.Watch() should not store watches if already started

The controller internal struct holds a list of watches
(as []watchDescription) when someone calls .Watch() to then start the
watches and informers once we're ready to call Start().

This behavior caused a memory leak in the case Watch was called after
a controller has already been started and if the source.Kind's cache was
either stopped or not available any longer. The leak was caused by the
watches internal slice holding on to all references to each watch ever
issued (and their respective caches).

Signed-off-by: Vince Prignano <[email protected]>

Author: vincepri

pkg/internal/controller/controller.go

@@ -113,13 +113,14 @@ func (c *Controller) Watch(src source.Source, evthdler handler.EventHandler, prc
 		}
 	}
 
-	c.watches = append(c.watches, watchDescription{src: src, handler: evthdler, predicates: prct})
-	if c.Started {
-		c.Log.Info("Starting EventSource", "source", src)
-		return src.Start(evthdler, c.Queue, prct...)
+	// Controller hasn't started yet, store the watches locally and return.
+	if !c.Started {
+		c.watches = append(c.watches, watchDescription{src: src, handler: evthdler, predicates: prct})
+		return nil
 	}
 
-	return nil
+	c.Log.Info("Starting EventSource", "source", src)
+	return src.Start(evthdler, c.Queue, prct...)
 }
 
 // Start implements controller.Controller
@@ -167,6 +168,9 @@ func (c *Controller) Start(stop <-chan struct{}) error {
 			}
 		}
 
+		// All the watches have been started, we can reset the local slice.
+		c.watches = nil
+
 		if c.JitterPeriod == 0 {
 			c.JitterPeriod = 1 * time.Second
 		}