Dead Letter Queue
A dead letter queue stores messages that cannot be processed, keeping poison messages from blocking normal handling and allowing later analysis and reprocessing.
Purpose
Isolate failed messages, preventing queue blockage and infinite retries.
Mechanism
When processing fails a set number of times (e.g., 3), the message moves to the DLQ instead of retrying forever. DLQ messages await manual analysis or re-delivery after a fix. SQS/Kafka/RabbitMQ support DLQs. Monitor DLQ length with alerts.
Use cases
- Message queues
- Fault isolation
- Exception handling
Related terms
Message Queue
A message queue decouples producers from consumers asynchronously: producers send messages to the queue, consumers process them in order, absorbing traffic spikes. GLOSSARY
AMQP
AMQP is an enterprise-grade message queue protocol that defines routing, queue, binding, and transaction semantics, implemented by RabbitMQ and others. GLOSSARY