Design a File Conversion Service

Problem

Design a scalable file conversion service (e.g., docs/images/video) as reported in Oracle design rounds.

Requirements

Functional:

• Upload a file, request a target format
• Asynchronous conversion with status polling
• Download the converted result
• Support large files

Non-functional:

• High throughput, variable file sizes
• Reliability: no lost jobs
• Scalable worker pool

Discussion points

1. Async job queue + worker pool (S3 + SQS pattern)
2. Status tracking and idempotency
3. Scaling workers by format/CPU cost
4. Error handling and retries
5. Storage lifecycle and cleanup