*: Fix data race between getting labels and setting labels in config (#…

…45563) (#45567)

close #45561

server/http_handler.go

@@ -2207,12 +2207,15 @@ func (h labelHandler) ServeHTTP(w http.ResponseWriter, req *http.Request) {
 
  if len(labels) > 0 {
  cfg := *config.GetGlobalConfig()
- if cfg.Labels == nil {
- cfg.Labels = make(map[string]string, len(labels))
- }
- for k, v := range labels {
- cfg.Labels[k] = v
+ // Be careful of data race. The key & value of cfg.Labels must not be changed.
+ if cfg.Labels != nil {
+ for k, v := range cfg.Labels {
+ if _, found := labels[k]; !found {
+ labels[k] = v
+ }
+ }
  }
+ cfg.Labels = labels
  config.StoreGlobalConfig(&cfg)
  logutil.BgLogger().Info("update server labels", zap.Any("labels", cfg.Labels))
  }

server/http_handler_test.go

@@ -24,6 +24,7 @@ import (
  "encoding/json"
  "fmt"
  "io"
+ "math/rand"
  "net"
  "net/http"
  "net/http/httptest"
@@ -1197,3 +1198,44 @@ func TestSetLabels(t *testing.T) {
  // reset the global variable
  config.GetGlobalConfig().Labels = map[string]string{}
 }
+
+func TestSetLabelsConcurrentWithGetLabel(t *testing.T) {
+ ts := createBasicHTTPHandlerTestSuite()
+
+ ts.startServer(t)
+ defer ts.stopServer(t)
+
+ testUpdateLabels := func() {
+ labels := map[string]string{}
+ labels["zone"] = fmt.Sprintf("z-%v", rand.Intn(100000))
+ buffer := bytes.NewBuffer([]byte{})
+ require.Nil(t, json.NewEncoder(buffer).Encode(labels))
+ resp, err := ts.postStatus("/labels", "application/json", buffer)
+ require.NoError(t, err)
+ require.NotNil(t, resp)
+ defer func() {
+ require.NoError(t, resp.Body.Close())
+ }()
+ require.Equal(t, http.StatusOK, resp.StatusCode)
+ newLabels := config.GetGlobalConfig().Labels
+ require.Equal(t, newLabels, labels)
+ }
+ done := make(chan struct{})
+ go func() {
+ for {
+ select {
+ case <-done:
+ return
+ default:
+ config.GetGlobalConfig().GetTiKVConfig()
+ }
+ }
+ }()
+ for i := 0; i < 100; i++ {
+ testUpdateLabels()
+ }
+ close(done)
+
+ // reset the global variable
+ config.GetGlobalConfig().Labels = map[string]string{}
+}