dmitrievanthony dmitrievanthony - 2 months ago 16
Java Question

Loss of messages in RabbitMQ

I try to build persistent message queue with some delay per message. In Java-code it's looks like this:

ConnectionFactory factory = new ConnectionFactory();
factory.setHost("localhost");
Connection connection = factory.newConnection();
Channel channel = connection.createChannel();

channel.exchangeDeclare("WorkExchange", "direct");
channel.queueDeclare("WorkQueue", true, false, false, null);
channel.queueBind("WorkQueue", "WorkExchange", "");

Map<String, Object> args = new HashMap<>();
args.put("x-dead-letter-exchange", "WorkExchange");

channel.exchangeDeclare("RetryExchange", "direct");
channel.queueDeclare("RetryQueue", true, false, false, args);
channel.queueBind("RetryQueue", "RetryExchange", "");

channel.confirmSelect();
BasicProperties properties = new BasicProperties();
properties.setDeliveryMode(2);
properties.setExpiration("120000");
channel.basicPublish("RetryExchange", "", properties, "Hello world!".getBytes());
channel.waitForConfirmsOrDie();
connection.close();


However, I have some problem with persistency. When I stop server, wait some time and start it again, messages which have to move to WorkQueue just disappear. What I do wrong? Or it's by design?

Answer

However, I have some problem with persistency. When I stop server, wait some time and start it again, messages which have to move to WorkQueue just disappear. What I do wrong? Or it's by design?

You should use MessageProperties for making your messages persistence.

channel.basicPublish("", "task_queue", 
        MessageProperties.PERSISTENT_TEXT_PLAIN,
        message.getBytes());

Your current code `channel.queueDeclare("RetryQueue", true, false, false, args); will make the queue persistence but not the message.

More here RabbitMQ Doc