[throwaway38375]

Because you can set up a rudimentary queueing system in MySQL/PostgreSQL very quickly these days. And it scales really well for small to medium sized applications!

I maintain a web application with a few hundred daily users and with the following table I have never had any problems:

CREATE TABLE `jobs` ( `id` BIGINT NOT NULL AUTO_INCREMENT, `queue` VARCHAR NOT NULL, `payload` JSON NOT NULL, `created_at` DATETIME NOT NULL, PRIMARY KEY `id`, INDEX `queue` );

Using MySQL's LOCK and UNLOCK I can ensure the same job doesn't get picked up twice.

All in all, it's a very simple solution. And simple is better!