处理错误和重试对于可靠的 RabbitMQ 消费者来说很重要——决定消息处理失败时该怎么办(重试、死信路由或丢弃)。适当的错误处理可防止消息丢失和消费者卡住。
问题
When a consumer fails to process a message (bad data, downstream failure, bug):
→ requeue forever → a "poison" message blocks the queue (retried endlessly)
→ discard → message LOST
→ crash → reprocess, possibly stuck again
→ need a deliberate strategy.
重试策略
✓ NACK + REQUEUE → reject and requeue for retry (but limit retries — don't requeue forever)
✓ RETRY WITH BACKOFF → retry transient failures with increasing delays (e.g. via a delayed
retry queue with TTL → requeue after a delay)
✓ RETRY LIMIT → track attempts; after N failures → DEAD LETTER (don't retry forever)
✓ Distinguish TRANSIENT (retry) vs PERMANENT (dead-letter immediately) failures
