ActiveMQ broker redelivery vs consumer redelivery

Question

I'm trying to understand the difference between ActiveMQ redeliveryPlugin and consumer's attempt to recieve messages before it marks it as a poison pill. What's the difference. In the documentation there'is an example:

<broker xmlns="http://activemq.apache.org/schema/core"    schedulerSupport="true" >
        .... 
        <plugins>
            <redeliveryPlugin fallbackToDeadLetter="true" sendToDlqIfMaxRetriesExceeded="true">
                <redeliveryPolicyMap>
                    <redeliveryPolicyMap>
                        <redeliveryPolicyEntries>
                            <!-- a destination specific policy -->
                            <redeliveryPolicy queue="SpecialQueue" maximumRedeliveries="4"
redeliveryDelay="10000" />
                        </redeliveryPolicyEntries>
                        <!-- the fallback policy for all other destinations -->
                        <defaultEntry>
                            <redeliveryPolicy maximumRedeliveries="4" initialRedeliveryDelay="5000"
redeliveryDelay="10000" />
                        </defaultEntry>
                    </redeliveryPolicyMap>
                </redeliveryPolicyMap>
            </redeliveryPlugin>
        </plugins>

Now, I uderstand the broker's redelivery system as a separate to the client's one. For instance, after making 6 attempts (by default) to acknowledge a message (CLIENT_ACKNOWLDGMENT mode) the consumer send a poison pill. So, is it true that after receiving the poison pill, broker will try to resend the message to the consumer which will make another 6 attempt.

So, in total we may have 4 x 6 = 24 attempts before the message will send to a DLQ.

Is my understading correct?

Answer 1

Yes. The broker is not aware of any client redelivery. That happens in "the driver" - in memory. The broker won't consider if the client has already retried or not. The result is nested retries which is good to be aware of.