sclass ReliableSingleThread_Multi<A> {
  IVF1<A> processObject;
  int delay; // delay before changes are processed
  
  // internal
  Set<A> changedObjects = synchroSet();
  ReliableSingleThread rst = new(r _process);

  // notify of change in object
  void add(A a) {
    if (syncAdd(changedObjects, a))
      rst.trigger();
  }
  
  // internal
  void _process {
    sleep(delay);
    for (A object : cloneAndClearList(changedObjects))
      pcallF(processObject, object);
  }
}