A nightly batch job starves the payment service at peak. Design priority and preemption so it cannot recur.

Priority is one number with three separate effects: scheduling order, preemption victim selection, and eviction order under node pressure. Conflating those is the trap; designing tiers that survive both a full cluster and a hot node is the pass.

Grounded in researched DevOps, SRE and platform engineering interview loops, written to a senior-engineer editorial bar, and never padded to hit a word count.