Implementing the small FR DISTMYSQL-182 as also suggested by customer in the comments, just adding the <db>.Ping() to check if the instance is really available or not.

Author: Tusamarco

go/inst/instance_dao.go

@@ -380,6 +380,7 @@ func ReadTopologyInstanceBufferable(instanceKey *InstanceKey, bufferWrites bool,
 
 	latency.Start("instance")
 	db, err := db.OpenDiscovery(instanceKey.Hostname, instanceKey.Port)
+	err = db.Ping()
 	latency.Stop("instance")
 	if err != nil {
 		goto Cleanup