Delayed::Job (or DJ) encapsulates the common pattern of asynchronously executing
longer tasks in the background.

It is a direct extraction from Shopify where the job table is responsible for a
multitude of core tasks. Amongst those tasks are:
- sending massive newsletters
- image resizing
- http downloads
- updating smart collections
- updating solr, our search server, after product changes
- batch imports
- spam checks

WWW: https://github.com/collectiveidea/delayed_job