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I’m a backend engineer building highly scalable distributed systems. I write about system design, databases, and infrastructure.
Delay Queues: Do It Later, Reliably
What is a delay queue? A delay queue holds a message/job until a specified delay time in the future, then makes it available for processing. It’s the simplest way to schedule “do this later” without blocking workers or rolling your own cron logic. Why use a delay queue? Retries with backoff — retry failed tasks after a delay. Scheduled tasks — run at specific times (e.g., reminder emails). Rate smoothing — spread out work to avoid thundering herds. When to choose what 1. Broker-based Delay Queues Built-in support for delayed messages in brokers. ...