Demo
Demo

Knowledge base

delayed-queues verified

How many steps the ladder has

in the configuration this is a linedelayed-queues: …

Number of delay steps declared at start-up; each step waits twice as long as the one before, so the count decides the longest single wait.

Values

Values
positive integer
applying
restart required
where it can be set
in the config file · with a startup flag · as an environment variable

In detail

Eleven steps reach 1024 seconds, a little over seventeen minutes, and any longer wait is made by chaining steps — a message can pass through several before returning. Observed on the stand as exactly eleven queues, outbox+0001 … outbox+1024, each with x-message-ttl equal to its name in seconds and a dead-letter routing key back to the sending queue. Adding steps extends the longest single hop; removing them makes long waits pass through more queues, which costs broker work rather than accuracy. The count cannot be changed on queues that already exist — RabbitMQ refuses to redeclare a queue with different arguments — so changing it means deleting the ladder first.

What happens if you get it wrong

Changed while the ladder already exists.The engine cannot redeclare the queues and fails to start; the fix is deleting the ladder, which throws away every message waiting in it.inference
Reduced far below the longest retry interval in use.Long waits are assembled from many short hops, so a message bounces between queues repeatedly instead of resting in one — more broker traffic for the same delay.inference · inference