Laravel Horizon is a kickass dashboard for viewing queued jobs. Co-creator Mohammed Said published two posts about the inner working of the tool. The first one on the Diving Laravel site highlights the overall configuration and how the master supervisor works.

Laravel Horizon is a queue manager that gives you full control over your queues, it provides means to configure how your jobs are processed, generate analytics, and perform different queue-related tasks from within a nice dashboard. In this dive we're going to learn how Horizon boots up and handles processing jobs using different workers as well as how it collects useful metrics for you to have the full picture of how your application dispatches and runs jobs.

https://divinglaravel.com/horizon/before-the-dive

The second one, published on his own blog, shows how queued jobs can get tagged.

Laravel Horizon is shipped with many amazing features that help you understand what goes on with your queue workers, my personal favorite feature is the ability to tag jobs for further investigation.

https://themsaid.com/tagging-jobs-in-laravel-horizon-20170731