AWS Lambda SnapStart: Java Cold Start Killer

AWS announced SnapStart for Lambda. It caches initialized snapshots of the JVM, reducing cold starts from 5+ seconds to under 200ms.

How It Works

When you publish a version, Lambda invokes your function, takes a snapshot of the memory/disk state (Firecracker microVM), and stores it. On cold start, it restores from snapshot instead of booting.

Caveat: Avoid storing secrets, timestamps, or random seeds during init—they will be frozen in the snapshot!