message: Call wake_up_notifier_worker rather than on_change so that the notifiers are processed on the correct thread.
diff: @@ -267,7 +267,7 @@ struct Subscription::Notifier : public _impl::CollectionNotifier {
  }
  // Trigger processing of change notifications.
  - m_coordinator->on_change();
  + m_coordinator->wake_up_notifier_worker();
  }
  std::exception_ptr error() const
  