From dd287c8364b3e9789bf8e182873dcc21f7acfdf2 Mon Sep 17 00:00:00 2001
From: Isaac Jimeno <ijimeno@redhat.com>
Date: Mon, 6 May 2024 10:50:37 +0200
Subject: [PATCH] DVO-209: CPU leak fix (#323)

* Fix request namespaces and sleep if nothing to validate

* Fix namespaces length setting

* Fix end loop on no namespace and logging info

* Minor refactor and cleaning debug comments

* Fix added elapsed time as a const
---
 pkg/controller/const.go              |  4 ++++
 pkg/controller/generic_reconciler.go | 15 ++++++++++++++-
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/pkg/controller/const.go b/pkg/controller/const.go
index 6ff8c3e8..d0f7f216 100644
--- a/pkg/controller/const.go
+++ b/pkg/controller/const.go
@@ -11,6 +11,10 @@ const (
 	// number of resource instances for any kubernetes resource
 	defaultListLimit = 5
 
+	// default time (in seconds) to skip the loop in the generic reconciler
+	// if there are no namespaces to validate in the cluster
+	defaultNoNamespacesElapseTime = 10
+
 	// EnvKubeClientQPS overrides defaultKubeClientQPS
 	EnvKubeClientQPS string = "KUBECLIENT_QPS"
 
diff --git a/pkg/controller/generic_reconciler.go b/pkg/controller/generic_reconciler.go
index 9aa17ac6..b0e5ebbc 100644
--- a/pkg/controller/generic_reconciler.go
+++ b/pkg/controller/generic_reconciler.go
@@ -9,6 +9,7 @@ import (
 	"strconv"
 	"strings"
 	"sync"
+	"time"
 
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
@@ -117,6 +118,19 @@ func (gr *GenericReconciler) Start(ctx context.Context) error {
 			return nil
 		default:
 			gr.logger.Info("Reconciliation loop has started")
+
+			// Skips validation if no valid namespaces in the cluster. Avoids CPU overusage
+			gr.watchNamespaces.resetCache()
+			if namespaces, err := gr.watchNamespaces.getWatchNamespaces(ctx, gr.client); err != nil {
+				gr.logger.Error(err, "getting watched namespaces")
+				continue
+
+			} else if namespaces == nil || len(*namespaces) == 0 {
+				gr.logger.Info("No namespaces to validate, skipping loop")
+				time.Sleep(defaultNoNamespacesElapseTime * time.Second)
+				continue
+			}
+
 			if err := gr.reconcileEverything(ctx); err != nil && !errors.Is(err, context.Canceled) {
 				// TODO: Improve error handling so that error can be returned to manager from here
 				// this is done to make sure errors caused by skew in k8s version on server and
@@ -177,7 +191,6 @@ func (gr *GenericReconciler) reconcileEverything(ctx context.Context) error {
 			"Kind", resource.Kind)
 	}
 
-	gr.watchNamespaces.resetCache()
 	namespaces, err := gr.watchNamespaces.getWatchNamespaces(ctx, gr.client)
 	if err != nil {
 		return fmt.Errorf("getting watched namespaces: %w", err)