Fix scaler leak during cache refresh (kedacore#5807)

Signed-off-by: Guillaume Jacquet <guillaume.jacquet@gmail.com>
Signed-off-by: Jorge Turrado <jorge_turrado@hotmail.es>

CHANGELOG.md

@@ -93,6 +93,7 @@ Here is an overview of all new **experimental** features:
 - **MongoDB Scaler**:  MongoDB url parses correctly `+srv` scheme ([#5760](https://github.com/kedacore/keda/issues/5760))
 - **New Relic Scaler**: Fix CVE-2024-6104 in github.com/hashicorp/go-retryablehttp ([#5944](https://github.com/kedacore/keda/issues/5944))
 - **ScaledJob**: Fix ScaledJob ignores failing trigger(s) error ([#5922](https://github.com/kedacore/keda/issues/5922))
+- **General**: Scalers are properly closed after being refreshed ([#5806](https://github.com/kedacore/keda/issues/5806))
 - **MongoDB Scaler**:  MongoDB url parses correctly `+srv` scheme ([#5760](https://github.com/kedacore/keda/issues/5760))
 
 ### Deprecations

pkg/scaling/scale_handler.go

@@ -293,23 +293,20 @@ func (h *scaleHandler) getScalersCacheForScaledObject(ctx context.Context, scale
 // performGetScalersCache returns cache for input scalableObject, it is common code used by GetScalersCache() and getScalersCacheForScaledObject() methods
 func (h *scaleHandler) performGetScalersCache(ctx context.Context, key string, scalableObject interface{}, scalableObjectGeneration *int64, scalableObjectKind, scalableObjectNamespace, scalableObjectName string) (*cache.ScalersCache, error) {
 	h.scalerCachesLock.RLock()
-	regenerateCache := false
+
 	if cache, ok := h.scalerCaches[key]; ok {
 		// generation was specified -> let's include it in the check as well
 		if scalableObjectGeneration != nil {
 			if cache.ScalableObjectGeneration == *scalableObjectGeneration {
 				h.scalerCachesLock.RUnlock()
 				return cache, nil
 			}
-			// object was found in cache, but the generation is not correct,
-			// we'll need to close scalers in the cache and
-			// proceed further to recreate the cache
-			regenerateCache = false
 		} else {
 			h.scalerCachesLock.RUnlock()
 			return cache, nil
 		}
 	}
+
 	h.scalerCachesLock.RUnlock()
 
 	if scalableObject == nil {
@@ -379,17 +376,17 @@ func (h *scaleHandler) performGetScalersCache(ctx context.Context, key string, s
 	default:
 	}
 
-	// Scalers Close() could be impacted by timeouts, blocking the mutex
-	// until the timeout happens. Instead of locking the mutex, we take
-	// the old cache item and we close it in another goroutine, not locking
-	// the cache: https://github.com/kedacore/keda/issues/5083
-	if regenerateCache {
-		oldCache := h.scalerCaches[key]
+	h.scalerCachesLock.Lock()
+	defer h.scalerCachesLock.Unlock()
+
+	if oldCache, ok := h.scalerCaches[key]; ok {
+		// Scalers Close() could be impacted by timeouts, blocking the mutex
+		// until the timeout happens. Instead of locking the mutex, we take
+		// the old cache item and we close it in another goroutine, not locking
+		// the cache: https://github.com/kedacore/keda/issues/5083
 		go oldCache.Close(ctx)
 	}
 
-	h.scalerCachesLock.Lock()
-	defer h.scalerCachesLock.Unlock()
 	h.scalerCaches[key] = newCache
 	return h.scalerCaches[key], nil
 }