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Amazon's Sandman served agentic RL sandboxes on shared Kubernetes, holding 11,858 concurrent environments and creating 3.1 million sandboxes for four SWE-bench Verified campaigns in October

AspireAI community · arXiv (Amazon)
Agentic reinforcement learning needs repeated tool calls inside task-specific environments, and a single training job can create thousands of them in bursts while sharing a cluster with other jobs. Sandman is the sandbox service Amazon built and operates for exactly that: each sandbox is a Kubernetes pod with a small daemon mounted into an unmodified task image, files and processes persist across calls, and the service handles creation, readiness and cleanup. In a scale test it held 11,858 concurrent tiny sandboxes, and four production SWE-bench Verified training campaigns created 3.1 million sandboxes during October 2026. The paper is a systems case study with the trade-offs and operational lessons rather than a quality benchmark, and the daemon, provider and pool are stated to be on the way to open source.
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