Kafka Retry and Dead Letter Queue (DLQ) Pattern

In this chapter

Retry the temporary. Park the broken.

What breaks

Some events fail for a moment (a database deadlock). Some are broken and will never work.

Three ways to respond

• Retry everything forever: A broken event blocks the line.
• Backoff for temporary, DLQ for broken: Work keeps moving. Bad events wait for a human. (the fix)
• Log and drop failures: Silent data loss.

The fix: Backoff for temporary, DLQ for broken

Backoff gives a struggling dependency time. A dead-letter queue moves “poison” events aside so the rest keep flowing.

Remember: Retry with backoff. Park poison in a DLQ.

More on Failures problems

• Kafka Simulator: Producers, Partitions and Consumer Groups
• How Uber, Netflix and Zomato Use Kafka: Real Architectures
• Kafka Interview Questions: 26 Real Production Problems
• Kafka vs a Message Queue: Why Events Stay After Reading
• Kafka Topics vs Partitions and Message Keys Explained
• Kafka Producer Batching: Async Send, linger.ms, batch.size
• Event-Driven Architecture with Kafka: Drop Sync Calls
• Kafka Fan-Out: One Event, Many Consumer Groups

Keep learning

• Previous: Kafka Consumer Lag: More Consumers Than Partitions
• Next: Kafka Log Compaction Explained: Latest Value per Key
• All Kafka tutorial chapters

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