Modal rebuilds sandbox infrastructure to scale 1 million concurrent sandboxes in seconds

KEY POINTS

1. Modal engineers rebuilt their sandbox platform to avoid centralized coordination (e.g., etcd-backed Kubernetes control planes), making each worker the source of truth and running many parallel schedulers.
2. In benchmarks the new architecture created 1 million sandboxes in under a minute with median startup-to-code under 0.5s and sustained tens of thousands of sandbox creations per second.
3. Shows a concrete alternative to extending Kubernetes for GenAI-scale workloads by decoupling coordination from execution and demonstrating sub‑second isolation at million‑sandbox scale.