A challenge often faced in multi-tenant SaaS is ensuring that each tenant gets a fair share of a platform's resources. At Salsify, we had to address this in our Delayed Job-based background task execution infrastructure. Because our customers have different use cases, they tend to run tasks of varying complexity and size. Over time we developed tenant-fairness job reservation strategies that made scaling our job system difficult if not impossible. In this post, I discuss how we managed to extend Delayed Job to solve for tenant fairness in a scalable manner.