fix datarace on issue indexer queue (#9490)

Author: lunny

modules/indexer/code/indexer.go

@@ -38,6 +38,8 @@ func Init() {
 		return
 	}
 
+	initQueue(setting.Indexer.UpdateQueueLength)
+
 	ctx, cancel := context.WithCancel(context.Background())
 
 	graceful.GetManager().RunAtTerminate(ctx, func() {

modules/indexer/code/queue.go

@@ -21,8 +21,11 @@ type repoIndexerOperation struct {
 
 var repoIndexerOperationQueue chan repoIndexerOperation
 
+func initQueue(queueLength int) {
+	repoIndexerOperationQueue = make(chan repoIndexerOperation, queueLength)
+}
+
 func processRepoIndexerOperationQueue(indexer Indexer) {
-	repoIndexerOperationQueue = make(chan repoIndexerOperation, setting.Indexer.UpdateQueueLength)
 	for {
 		select {
 		case op := <-repoIndexerOperationQueue: