From 544ea424826ef60d703c5f4fb91b2c6a95f303aa Mon Sep 17 00:00:00 2001
From: Marek Siarkowicz <siarkowicz@google.com>
Date: Fri, 24 May 2024 10:16:48 +0200
Subject: [PATCH] Use normal Mutex instead of RWMutex

There is no benefit of having RWMutex as we have one reader and multiple
writers. In such cases RWMutex has worse performance than Mutex.
---
 .../apiserver/pkg/storage/cacher/watch_progress.go   | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/staging/src/k8s.io/apiserver/pkg/storage/cacher/watch_progress.go b/staging/src/k8s.io/apiserver/pkg/storage/cacher/watch_progress.go
index 0946eecc253..4c7121f14bb 100644
--- a/staging/src/k8s.io/apiserver/pkg/storage/cacher/watch_progress.go
+++ b/staging/src/k8s.io/apiserver/pkg/storage/cacher/watch_progress.go
@@ -42,7 +42,7 @@ func newConditionalProgressRequester(requestWatchProgress WatchProgressRequester
 		requestWatchProgress: requestWatchProgress,
 		contextMetadata:      contextMetadata,
 	}
-	pr.cond = sync.NewCond(pr.mux.RLocker())
+	pr.cond = sync.NewCond(&pr.mux)
 	return pr
 }
 
@@ -59,7 +59,7 @@ type conditionalProgressRequester struct {
 	requestWatchProgress WatchProgressRequester
 	contextMetadata      metadata.MD
 
-	mux     sync.RWMutex
+	mux     sync.Mutex
 	cond    *sync.Cond
 	waiting int
 	stopped bool
@@ -82,8 +82,8 @@ func (pr *conditionalProgressRequester) Run(stopCh <-chan struct{}) {
 	defer timer.Stop()
 	for {
 		stopped := func() bool {
-			pr.mux.RLock()
-			defer pr.mux.RUnlock()
+			pr.mux.Lock()
+			defer pr.mux.Unlock()
 			for pr.waiting == 0 && !pr.stopped {
 				pr.cond.Wait()
 			}
@@ -97,8 +97,8 @@ func (pr *conditionalProgressRequester) Run(stopCh <-chan struct{}) {
 		case <-timer.C():
 			timer.Reset(progressRequestPeriod)
 			shouldRequest := func() bool {
-				pr.mux.RLock()
-				defer pr.mux.RUnlock()
+				pr.mux.Lock()
+				defer pr.mux.Unlock()
 				return pr.waiting > 0 && !pr.stopped
 			}()
 			if !shouldRequest {