# One kustomize-controller can't keep up with thousands of Kustomizations. How does Flux split the work?

Flux CD, Hard (Expert), Architecture. https://k8wiz.com/uquiz/one-kustomize-controller-cant-keep-up-with-thousands-of-kustomizations-how-does-flux-split-the-work

- A. More replicas of the Deployment, which share objects through leader election
- B. Extra controller instances, each with --watch-label-selector for one sharding.fluxcd.io/key value
- C. One controller per namespace, which Flux starts on its own
- D. A spec.shard field on each Kustomization naming a controller pod

**Answer:** Extra controller instances, each with --watch-label-selector for one sharding.fluxcd.io/key value

**Explanation:** You label Flux objects with sharding.fluxcd.io/key, run additional controller instances that only watch their shard through --watch-label-selector, and make the main instance skip those labels. Extra replicas of one Deployment don't help, because only the leader reconciles.