@Service
public class EmailService {

    private final DataRepository dataRepository;

    public void drainDataToFile() {
        Thread newThread = new Thread(() -> {
           long lastId = 0;
           while (true) {
               try {
                   List<Record> records = dataRepository.findByIdGt(lastId, limit);
                   txtFile.save(records);
                   if (records.size() < limit) {
                     break;
                   }
                   lastId = records.last().getId();
               } catch (InterruptedException e) {
                   break;
               } catch (Throwable e) {
                   System.out.println("error: " + e);
               }
           }
        });
        newThread.setName("mail-sender");
        newThread.start();
    }
}