When retry is enabled within the binder, the listener container thread is suspended for any back off periods that are configured. This might be important when strict ordering is required with a single consumer. However, for other use cases, it prevents other messages from being processed on that thread. An alternative to using binder retry is to set up dead lettering with time to live on the dead-letter queue (DLQ) as well as dead-letter configuration on the DLQ itself. See “Section 3.1, “RabbitMQ Binder Properties”” for more information about the properties discussed here. You can use the following example configuration to enable this feature:
autoBindDlq
to true
.
The binder create a DLQ.
Optionally, you can specify a name in deadLetterQueueName
.dlqTtl
to the back off time you want to wait between redeliveries.dlqDeadLetterExchange
to the default exchange.
Expired messages from the DLQ are routed to the original queue, because the default deadLetterRoutingKey
is the queue name (destination.group
).
Setting to the default exchange is achieved by setting the property with no value, as shown in the next example.To force a message to be dead-lettered, either throw an AmqpRejectAndDontRequeueException
or set requeueRejected
to true
(the default) and throw any exception.
The loop continue without end, which is fine for transient problems, but you may want to give up after some number of attempts.
Fortunately, RabbitMQ provides the x-death
header, which lets you determine how many cycles have occurred.
To acknowledge a message after giving up, throw an ImmediateAcknowledgeAmqpException
.
The following configuration creates an exchange myDestination
with queue myDestination.consumerGroup
bound to a topic exchange with a wildcard routing key #
:
--- spring.cloud.stream.bindings.input.destination=myDestination spring.cloud.stream.bindings.input.group=consumerGroup #disable binder retries spring.cloud.stream.bindings.input.consumer.max-attempts=1 #dlx/dlq setup spring.cloud.stream.rabbit.bindings.input.consumer.auto-bind-dlq=true spring.cloud.stream.rabbit.bindings.input.consumer.dlq-ttl=5000 spring.cloud.stream.rabbit.bindings.input.consumer.dlq-dead-letter-exchange= ---
This configuration creates a DLQ bound to a direct exchange (DLX
) with a routing key of myDestination.consumerGroup
.
When messages are rejected, they are routed to the DLQ.
After 5 seconds, the message expires and is routed to the original queue by using the queue name as the routing key, as shown in the following example:
Spring Boot application.
@SpringBootApplication @EnableBinding(Sink.class) public class XDeathApplication { public static void main(String[] args) { SpringApplication.run(XDeathApplication.class, args); } @StreamListener(Sink.INPUT) public void listen(String in, @Header(name = "x-death", required = false) Map<?,?> death) { if (death != null && death.get("count").equals(3L)) { // giving up - don't send to DLX throw new ImmediateAcknowledgeAmqpException("Failed after 4 attempts"); } throw new AmqpRejectAndDontRequeueException("failed"); } }
Notice that the count property in the x-death
header is a Long
.