Design a Task Scheduling Service

Last updated: December 30, 2025

Quick Overview

Design a high-throughput task scheduling system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.

SpaceX
System Design
Software Engineer
SpaceX
December 30, 2025
Software Engineer
Technical Screen
System Design
Hard

7

7

479 solved


Design a high-throughput task scheduling system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.

System design interviews at SpaceX typically last 45-60 minutes. You are expected to drive the conversation, starting from requirements gathering through to a detailed architecture. The interviewer will evaluate your ability to handle ambiguity and make practical engineering decisions.

What the Interviewer Expects
  • Drive the design discussion proactively with minimal interviewer guidance
  • Perform detailed capacity estimation and use it to inform design decisions
  • Design for global scale with multi-region deployment and data consistency
  • Deep dive into 2-3 critical components with implementation-level detail
  • Address complex trade-offs: CAP theorem, eventual consistency, conflict resolution
  • Discuss operational excellence: deployment strategy, chaos engineering, SLOs/SLIs
  • Propose a phased rollout plan from MVP to full-scale system
Key Topics to Cover
Security and authentication
API design and rate limiting
Partitioning and sharding strategies
Database selection and data modeling
Consistency models and replication
How to Approach This
  1. Start by clarifying functional and non-functional requirements with the interviewer.
  2. Estimate the scale: QPS, storage, bandwidth. This drives your design decisions.
  3. Draw a high-level architecture first, then deep dive into 1-2 critical components.
  4. Discuss trade-offs explicitly (e.g., consistency vs availability, SQL vs NoSQL).
  5. Address failure scenarios, monitoring, and how the system handles 10x traffic spikes.
Possible Follow-up Questions
  • How would you migrate from a monolithic to a microservices architecture?
  • How do you ensure data consistency across multiple services?
  • How would you implement rate limiting to protect the system?
  • What happens if one of your database nodes goes down?
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Sample Answer
Requirements Clarification

Before diving into the architecture, clarify the scope with the interviewer. For Task Scheduling Service, key functional requirements include: what ar...

Capacity Estimation

Estimate the scale to drive design decisions. Assume 100M DAU with an average of 10 actions per user per day = 1B requests/day ~ 12K QPS average, ~36K...


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