-mutex cerr_mutex;
-map<thread::id, int> thread_name_map;
-int next_thread_num = 0;
-map<const void *, int> instance_name_map;
-int next_instance_num = 0;
+static mutex log_mutex;
+static map<thread::id, int> thread_name_map;
+static int next_thread_num = 0;
+static map<const void *, int> instance_name_map;
+static int next_instance_num = 0;