List buffer = new ArrayList();
while (true) {
    final ConsumerRecords consumerRecords =
            consumer.poll(1000);

    if (consumerRecords.count() > 0) {
        buffer.add(rs.iterator().next());
    }

    consumer.commitAsync();
    if (buffer.size() >= so luong phan tu can lay) {
        break;
    }
}

consume buffers
buffers.clear();