Dead Letter Queue

What

• handle message failure

• A queue which other queues (source queues) can target for messages that cannot process (be consumed) successfully.

Uses

• to set aside and isolate messages that cannot be processed correctly to determine why their processes failed

• Instead of trying to process messages that fail until they expire, move them to a dead-letter queue after a few process attempts.

  • This can reduce load on consumer/queue having to constantly retry the message, save costs if managed service

• troubleshoot incorrect message transmission operations.

Examples

• Configure an alarm for any messages delivered to a dead-letter queue

• Examine logs for exceptions that might have caused messages to be delivered to a dead-letter queue.

• Analyze the contents of messages delivered to a dead-letter queue to diagnose software or the producer’s or consumer’s hardware issues

• Determine whether you have given your consumer sufficient time to process messages

Not to use

• to decrease the number of messages and to reduce the possibility that you expose your system to messages that you can receive but cannot process.

• with standard queues when you want to retry the transmission of a message indefinitely

• with a FIFO queue if you do not want to break the exact order of messages or operations