[rabbitmq-discuss] Scheduled/postponed messages

Jon Brisbin jon at jbrisbin.com
Mon Apr 25 14:58:10 BST 2011

This sounds to me like the function of a queue type that buffers messages until a specific threshold is reached (either of number or of time window). Ideally, this should be implemented in the broker.

That wouldn't be an immediate fix, unfortunately, as implementing a new queue type is non-trivial.


On Apr 25, 2011, at 6:02 AM, Konstantin Tjuterev wrote:

> Hi, I'm trying to implement the following scenario with RabbitMQ:
> - a site which generates various emails according to user actions (like registration, ordering etc.), or according to schedule (daily announcements); emails are published into an RabbitMQ exchange
> - a set of workers which read the queue and send out emails, do some logging
> - some emails need to be sent immediately
> - some should be sent precisely at specific time (or as close as possible), like daily announcement should go out exactly at 8:00AM
> - generating daily announcements involves complex logic and takes some time (more than actual delivery), so there is a job which prepares it before time X and publishes into an exchange
> So, my question is if there is a native way to schedule messages to be delivered to workers exactly at specific time? If there is not, which strategy do you think would be the best:
> - declaring a separate queue for such scheduled/postponed messages and starting workers at required time (by cron)
> - having a check-what-time-is-it/sleep cycle in the workers (which are always running)
> - having workers consume the message, check time and do NOT send acknowledgement if it's not yet the time to process it (this is the only strategy I see, NOT requiring separate workers, but it will use a lot of resources for retrying message delivery)
> - anything else?
> Thanks in advance,
> Konstantin.
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Jon Brisbin

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