RabbitMQ queues

Queues buffer messages until consumers process them. Durable queues survive broker restarts when combined with persistent messages. Exclusive queues tie to one connection; auto-delete queues vanish when unused. TTL can expire messages or queue entries; max-length policies drop or dead-letter overflow.

Quorum queues trade classic mirrored queues for Raft-based replication and stronger data safety. Lazy queues move messages to disk sooner for very large backlogs. Consumer priority and single-active-consumer modes change fairness under load.

On interviews: explain durability versus persistence, when to use quorum queues, and how TTL and max-length protect the broker from unbounded growth.

Common pitfalls: durable queue with transient messages; no max-length on high-volume ingress; exclusive queues in horizontally scaled workers; ignoring dead-letter behavior when messages expire.

The trade-off is flexibility versus complexity—know when the simpler path is enough.

Checklist:

• Set durability and persistence consistently.
• Configure TTL and max-length for burst protection.
• Choose quorum versus classic with failover needs in mind.
• Document who owns queue declaration and lifecycle.