RLock() for readonly operation (#11603)

Co-authored-by: Radosław Kapka <rkapka@wp.pl>

container/queue/priority_queue.go

@@ -152,8 +152,8 @@ func (pq *PriorityQueue) PopByKey(key string) (*Item, error) {
 // RetrieveByKey searches the queue for an item with the given key and returns it
 // from the queue if found. Returns nil if not found.
 func (pq *PriorityQueue) RetrieveByKey(key string) *Item {
-	pq.lock.Lock()
-	defer pq.lock.Unlock()
+	pq.lock.RLock()
+	defer pq.lock.RUnlock()
 
 	item, ok := pq.dataMap[key]
 	if !ok {