static void cancelThread(Thread t) {
  if (t == null) ret;
  ping();
  ifndef LeanMode
  /*O mc = getWeakRef((WeakReference) vm_generalWeakSubMap("thread2mc").get(t));
  ifdef cancelThread_verbose
  print("cancelThread: mc=" + mc);
  endifdef
  if (mc != null) {
    Map ping_actions = cast get(mc, 'ping_actions);
    synchronized(ping_actions) {
      ping_actions.put(t, "cancelled");
      set(mc, ping_anyActions := true);
    }
  } else*/ synchronized(ping_actions) {
    ping_actions.put(t, "cancelled");
    ping_anyActions = true;
  }
  endifndef
}