多个消费者无法提高性能

Question

我正在尝试使用多个使用者来消耗来自Rabbit mq的消息。

在我的基本用例中：我们的队列中有5万条消息，每个使用者从队列中读取一条消息，并用50个DB查询执行算法，然后将ack发送给Rabbit mq。

我的问题是5个消费者，10个消费者，20个消费者的ack / sec保持不变，即11 Ack / sec。

我尝试在算法中评论我的插入查询。因此，我认为代码中没有锁定问题。

    public void init() {
        try {
            factory.setUri(System.getenv("CLOUDAMQP_URL"));
            connection = factory.newConnection();
        } catch (IOException | TimeoutException | KeyManagementException | NoSuchAlgorithmException
                | URISyntaxException e) {
            log.error(e.getMessage(), e);
        }
    }

    public void processJobInstance() {
        for (int i = 0; i < batchJobInstanceList.size(); i++) {

                for (int c = 0; c < NUMBER_OF_CONSUMERS_PER_JOB; c++) {
                    try {
                        /*
                         * Do not close channel here as doWork is a future task. We will close channel in handle
                         * delivery.
                         */
                        Channel channel = connection.createChannel();
                        final Consumer consumer = createConsumerBean(channel, batchJobInstance.getId());
        boolean autoAck = false;
        channel.basicQos(1);
        channel.basicConsume(batchJobInstance.getId(), autoAck, consumer);
                    } catch (Exception e) {
                        log.error("Channel failed by Exception.", e);
                    }
                }
        }
    }

        @Bean
    @Scope("prototype")
    public Consumer createConsumerBean(Channel channel, final String id) {
        return new DefaultConsumer(channel) {

            @Override
            public void handleDelivery(String consumerTag, Envelope envelope, AMQP.BasicProperties properties,
                    byte[] body) throws IOException {

                try {
// Algo with 50 select calls and 5-10 insert                

                } catch (Exception ex) {
                    log.error("HandleDelivery failed by Exception.", ex);
                } finally {
                    channel.basicAck(envelope.getDeliveryTag(), false);
                }
            }

            @Override
            public void handleCancel(String consumerTag) throws IOException {
                log.info("Cancelled: " + consumerTag);
            }
        };
    }

我的代码有什么问题，那就是越来越多的使用者无法改善性能？