Question

我有高优先级的消息，需要处理的优先级高于低优先级的消息，但是在MessageProducer上设置优先级似乎没有任何影响，并且消息的使用顺序与发送到队列的顺序相同。

下面是我的代码：

package com.example.jms;

import javax.jms.ConnectionFactory;
import javax.jms.DeliveryMode;
import javax.jms.JMSException;
import javax.jms.MessageProducer;
import javax.jms.Session;
import javax.jms.TextMessage;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.jms.DefaultJmsListenerContainerFactoryConfigurer;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.context.annotation.Bean;
import org.springframework.jms.config.DefaultJmsListenerContainerFactory;
import org.springframework.jms.config.JmsListenerContainerFactory;
import org.springframework.jms.core.JmsTemplate;
import org.springframework.jms.core.ProducerCallback;
import org.springframework.jms.support.converter.MappingJackson2MessageConverter;
import org.springframework.jms.support.converter.MessageConverter;
import org.springframework.jms.support.converter.MessageType;

@SpringBootApplication
public class JmsPriorityApplication {

    private static final Logger logger= LoggerFactory.getLogger(JmsPriorityApplication.class);

    public static void main(String[] args) {

        // Launch the application
        ConfigurableApplicationContext context = SpringApplication.run(JmsPriorityApplication.class, args);

        JmsTemplate jmsTemplate = context.getBean(JmsTemplate.class);
        // Send a message with a POJO - the template reuse the message converter
        System.out.println("Sending an email message.");

        jmsTemplate.execute("mailbox", new ProducerCallback<Object>() {

            @Override 
            public Object doInJms(Session session, MessageProducer producer) throws JMSException { 
                String text = "Hello this msg1";
                int priority=1;
                TextMessage message1 = session.createTextMessage(text);
                producer.send(message1, DeliveryMode.PERSISTENT, priority, 0);
                logger.info("{} sent with priority={}", text, priority);

                text = "Hello this msg2";
                priority=9;
                TextMessage message2 = session.createTextMessage(text);
                producer.send(message2, DeliveryMode.PERSISTENT, priority, 0);
                logger.info("{} sent with priority={}", text, priority);
                return null;
            }

        } );

    }


    @Bean
    public JmsListenerContainerFactory<?> myFactory(ConnectionFactory connectionFactory,
            DefaultJmsListenerContainerFactoryConfigurer configurer) {
        DefaultJmsListenerContainerFactory factory = new DefaultJmsListenerContainerFactory();
        // This provides all boot's default to this factory, including the message converter
        configurer.configure(factory, connectionFactory);
        // You could still override some of Boot's default if necessary.
        return factory;
    }

}

Receiver.java

package com.example.jms;

import org.springframework.jms.annotation.JmsListener;
import org.springframework.stereotype.Component;

@Component
public class Receiver {

    @JmsListener(destination = "mailbox", containerFactory = "myFactory")
    public void receiveMessage(String msg) {
        System.out.println("Received <" + msg + ">");
    }

}

下面是输出：

Sending an email message.
2019-02-05 17:42:44.161  INFO 7828 --- [           main] com.example.jms.JmsPriorityApplication   : Hello this msg1 sent with priority=1
2019-02-05 17:42:44.161  INFO 7828 --- [           main] com.example.jms.JmsPriorityApplication   : Hello this msg2 sent with priority=9
Received <Hello this msg1>
Received <Hello this msg2>

我期望在msg1之前收到msg2。我不确定我在这里缺少什么。注意：发送消息时使用者处于活动状态。

Answer 1

由于消费者在发送消息时处于活动状态，因此几乎可以确定，在第二个消息到达代理之前，代理正在将第一个消息分发给客户端。这意味着，由于客户端已经收到了较低优先级的消息，因此基本上没有时间让较高优先级的消息抢占较低优先级的消息。

通常，只有当队列中有消息堆积时，优先传递的想法才有意义。为了进行测试，您应该在所有消息都已发送之前不激活使用者（此任务需要某种外部协调或手动干预），或者增加消息量，以便在优先发送中可以在队列中积累足够的消息。真的发生了。

设置MessageProducer优先级对消息没有影响

1 个答案: