SAA-C03 Q128 · Serverless

Question

A company is developing a latency-sensitive application. Part of the application includes several AWS Lambda functions that need to initialize as quickly as possible. The Lambda functions are written in Java and contain initialization code outside the handlers to load libraries, initialize classes, and generate unique IDs. Which solution will meet the startup performance requirement MOST cost-effectively?

Accepted Answer

**Option D** correctly addresses all requirements:

1. **Lambda SnapStart** is specifically designed for Java Lambda functions to eliminate cold start latency. It works by taking a Firecracker microVM snapshot after the initialization phase completes, then restoring from that snapshot instead of re-initializing — reducing cold start from seconds to milliseconds.

2. **Pre-snapshot hook (beforeCheckpoint)**: The `CRaC` (Coordinated Restore at Checkpoint) API allows you to run code just before the snapshot is taken. This is perfect for loading libraries and initializing classes — they get captured in the snapshot.

3. **Moving unique ID generation into the handler**: This is CRITICAL. If unique IDs are generated during initialization, they get baked into the snapshot. Every restored instance

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