← Openai Interview Insights

Openai·Software Engineer·Onsite - System Design / Architecture·Senior

SeniorPrefer not to say
Apr 2026

Summary

OpenAI system design round for a software engineer role. The prompt came pre-loaded with API and functional requirements, so most of the session was spent on fault tolerance and worker reliability, which is where things got interesting.

Questions Asked (1)

Q1

Design a video generation system similar to Sora, with a focus on handling worker failures and crashes during long-running generation jobs.

System DesignTechnical Trade-offsAPI & Integrations
Author's notes

The API and functional requirements were already written out in the prompt, so I didn't have to spend time scoping.

Create a free account to read the full note

AI HintsAI Generated

Suggested Approach

Start by clarifying requirements and scale, then design a high-level architecture for video generation with a focus on fault tolerance. Emphasize checkpointing, idempotency, and distributed coordination to handle worker failures during long-running jobs.

Pro tip: Demonstrate maturity by discussing trade-offs between checkpoint frequency and overhead, and how to handle partial failures without restarting entire jobs. Mention that you'd monitor failure rates and use exponential backoff for retries.

1. Clarify Requirements and Scale

Ask about expected job duration, video resolution, throughput, and failure rates. Establish SLAs and consistency requirements.

2. High-Level Architecture

Outline components: job queue, scheduler, worker pool, storage for checkpoints and outputs, and a metadata database. Explain how jobs are split into stages.

3. Fault Tolerance Mechanisms

Describe checkpointing (e.g., saving model states and intermediate frames), idempotent operations, and worker health monitoring with heartbeats.

4. Failure Recovery Workflow

Detail how a failed worker's job is detected, reassigned, and resumed from the last checkpoint. Discuss retry policies and dead-letter queues.

5. Trade-offs and Optimizations

Discuss trade-offs: checkpoint frequency vs. overhead, at-least-once vs. exactly-once semantics, and cost of redundancy. Mention optimizations like adaptive checkpointing.

Key Points to Mention

  • Checkpointing and resuming long-running jobs from saved state
  • Idempotency and exactly-once processing to avoid duplicate work
  • Distributed coordination (e.g., using a coordinator like ZooKeeper or etcd)
  • Worker health monitoring with heartbeats and timeouts
  • Retry policies with exponential backoff and jitter
  • Storage considerations for checkpoints and generated videos (e.g., object storage, versioning)

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.