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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 problem was dressed up as 'design Sora' but really it's a task scheduler under the hood, and if you miss that you're already behind.

Questions Asked (1)

Q1

Design a video generation scheduling system (like Sora): focus on what happens when compute resources are exhausted and how worker preemption is handled, including task re-queuing and user notification on completion.

System DesignTechnical Trade-offs
Author's notes

The 'design Sora' framing almost got me spending time on the ML pipeline stuff, which is a trap.

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AI HintsAI Generated

Suggested Approach

Start by clarifying requirements and scale, then design a high-level architecture with a job queue, scheduler, and worker pool. Focus on the preemption mechanism: when resources are exhausted, lower-priority tasks are preempted, re-queued with preserved state, and users are notified upon completion. Discuss trade-offs between fairness, latency, and resource utilization.

Pro tip: Emphasize idempotency and checkpointing to ensure preempted tasks can resume without duplicating work, and design notifications to be reliable and non-intrusive, possibly with progress updates.

1. Clarify Requirements and Scale

Ask about expected job volume, video generation complexity, latency SLAs, and user priorities. Define what 'compute resources exhausted' means (e.g., GPU memory, worker count).

2. High-Level Architecture

Propose a distributed system with a job queue (e.g., Kafka, RabbitMQ), a scheduler that assigns tasks to workers, and a metadata store for job states. Include a notification service.

3. Preemption and Re-queuing Strategy

Design a priority-based preemption: when resources are low, preempt lower-priority tasks. Save task state (checkpoints) to allow resumption. Re-queue preempted tasks with updated priority or backoff.

4. User Notification on Completion

Ensure users are notified when their video is ready, even after preemption. Use a reliable message queue or webhook with retries. Consider progress updates and estimated completion times.

5. Trade-offs and Failure Handling

Discuss trade-offs: preemption overhead vs. resource utilization, fairness vs. priority. Handle failures: worker crashes, duplicate notifications, and state corruption.

Key Points to Mention

  • Priority queues and preemption policies (e.g., preempt lowest priority first)
  • Checkpointing and idempotent task execution to resume after preemption
  • Re-queuing with exponential backoff to avoid thrashing
  • Notification service with at-least-once delivery and deduplication
  • Monitoring and autoscaling to mitigate resource exhaustion
  • Trade-offs between latency, fairness, and cost

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