ActiveMQ Artemis max-redelivery-delay and deadletterqueue

We are using the broker ActiveMQ Artemis 2.26.0, and I'm trying to set up a redelivery mechanism on a queue.

I would like for some messages to be retried for 72h maximum with progressive back-off. After 72h the message should be sent to a DLQ.

The doc states that both mechanisms of message redelivery and dead-letter queue can be combined, so I tried the following, using the examples provided with ActiveMQ Artemis:

broker.xml:

      <address-settings>
         <!--override the redelivery-delay  for the example queue-->
         <address-setting match="exampleQueue">
            <redelivery-delay>30000</redelivery-delay>
            <redelivery-delay-multiplier>2.5</redelivery-delay-multiplier>
            <dead-letter-address>deadLetterQueue</dead-letter-address>
            <max-redelivery-delay>259200000</max-redelivery-delay>
         </address-setting>
      </address-settings>

      <addresses>
         <address name="deadLetterQueue">
            <anycast>
               <queue name="deadLetterQueue"/>
            </anycast>
         </address>
         <address name="exampleQueue">
            <anycast>
               <queue name="exampleQueue"/>
            </anycast>
         </address>
      </addresses>

It seems that with this configuration the message are sent to deadLetterQueue after 10 redeliveries (default value of max-delivery-attempts).

How do I combine these values to fit my scenario?

TL; DR; you need to set a max-delivery-attempts value greater then 10

The total delivery delay is a geometric series so it is <redelivery-delay>*(1-<redelivery-delay-multiplier>^<max-delivery-attempts>)/(1-<redelivery-delay-multiplier>)

In your case the total delivery delay is 30000*(1-2.5^10)/(1-2.5)=190714863 that is less then 72h (259200000) so to fit your scenario you need to set a max-delivery-attempts value greater then 10, i.e. with max-delivery-attempts = 11 the total delivery delay is 476817158 (132h) that is greater than 72h.

To set up a redelivery mechanism on a queue in ActiveMQ Artemis 2.26.0 that retries messages for a maximum of 72 hours with progressive back-off, and then sends the message to a dead-letter queue (DLQ), you can use the following configuration:

<!-- begin snippet: js hide: false console: true babel: false -->

<!-- language: lang-html -->

<address-settings>
   <address-setting match="exampleQueue">
      <redelivery-delay>30000</redelivery-delay>
      <redelivery-delay-multiplier>2</redelivery-delay-multiplier>
      <max-redelivery-delay>259200000</max-redelivery-delay>
      <max-delivery-attempts>0</max-delivery-attempts>
      <dead-letter-address>deadLetterQueue</dead-letter-address>
      <expiry-delay>259200000</expiry-delay>
   </address-setting>
</address-settings>

<addresses>
   <address name="deadLetterQueue">
      <anycast>
         <queue name="deadLetterQueue"/>
      </anycast>
   </address>
   <address name="exampleQueue">
      <anycast>
         <queue name="exampleQueue"/>
      </anycast>
   </address>
</addresses>

<!-- end snippet -->

Explanation of the configuration:
redelivery-delay: This sets the initial delay between redelivery attempts in milliseconds. In this example, it is set to 30,000ms (30 seconds).
redelivery-delay-multiplier: This sets the rate at which the delay between redelivery attempts increases over time. In this example, it is set to 2, which means that the delay will double after each redelivery attempt.
max-redelivery-delay: This sets the maximum delay between redelivery attempts in milliseconds. In this example, it is set to 259,200,000ms (72 hours).
max-delivery-attempts: This sets the maximum number of times a message can be redelivered before being sent to the DLQ. In this example, it is set to 0, which means that there is no limit to the number of redelivery attempts.
dead-letter-address: This sets the address of the DLQ where messages that have exceeded the maximum number of redelivery attempts or the maximum time for redelivery are sent.
expiry-delay: This sets the time in milliseconds after which messages that have not been consumed are automatically expired and sent to the DLQ. In this example, it is set to the same value as max-redelivery-delay.
With this configuration, messages will be retried with progressive back-off for a maximum of 72 hours or until they are consumed, and then sent to the DLQ if they have not been consumed by that time. There is no limit to the number of redelivery attempts, so the delay between attempts will continue to increase until the maximum delay is reached.