Queues and workers

A server runs pools of workers, each serving its queues in order, so a busy first queue can keep the others waiting. Weights shares a pool between its queues instead: under load each queue gets about its weight's share of the claims, and a queue with nothing to do leaves its share to the others.

kiln.ServerConfig{Pools: []kiln.Pool{{
    Queues:  []string{"critical", "default", "low"},
    Workers: 20,
    Weights: map[string]int{"critical": 6, "default": 3},
}}}