Now actually fix race condition

main.go

@@ -18,8 +18,7 @@ func init() {
 func main() {
 	flag.Parse()
 	var wg sync.WaitGroup
-	var renamedFiles map[string]struct{} = make(map[string]struct{})
+	var renamedFiles sync.Map
-	var mapMutex sync.RWMutex
 	extensionRegex := regexp.MustCompile(`\.[a-zA-Z0-9]+$`)
 
 	wg.Wait()
@@ -68,11 +67,8 @@ func main() {
 				log.Printf("File %s already exists", newFile)
 				return
 			}
-			log.Printf("%#v", newFile)
 
-			mapMutex.RLock()
+			_, ok := renamedFiles.Load(newFile)
-			_, ok := renamedFiles[newFile]
-			mapMutex.RUnlock()
 			if ok {
 				log.Printf("File %s already renamed", newFile)
 				return
@@ -82,10 +78,8 @@ func main() {
 				log.Printf("File %s already has the correct name", file)
 				return
 			}
+			renamedFiles.Store(newFile, struct{}{})
 			log.Printf("%s -> %s", file, newFile)
-			mapMutex.Lock()
-			renamedFiles[newFile] = struct{}{}
-			mapMutex.Unlock()
 			err = os.Rename(file, newFile)
 			if err != nil {
 				log.Printf("Error renaming file %s to %s: %s", file, newFile, err)