session: Do not run telemetry loops when it's disabled in config (#40156

) (#41148)

close #40155

session/session.go

@@ -3340,10 +3340,14 @@ func BootstrapSession(store kv.Storage) (*domain.Domain, error) {
 	if dom.GetEtcdClient() != nil {
 		// We only want telemetry data in production-like clusters. When TiDB is deployed over other engines,
 		// for example, unistore engine (used for local tests), we just skip it. Its etcd client is nil.
-		go func() {
-			dom.TelemetryReportLoop(ses[5])
-			dom.TelemetryRotateSubWindowLoop(ses[5])
-		}()
+		if config.GetGlobalConfig().EnableTelemetry {
+			// There is no way to turn telemetry on with global variable `tidb_enable_telemetry`
+			// when it is disabled in config. See IsTelemetryEnabled function in telemetry/telemetry.go
+			go func() {
+				dom.TelemetryReportLoop(ses[5])
+				dom.TelemetryRotateSubWindowLoop(ses[5])
+			}()
+		}
 	}
 
 	// setup plan replayer handle