Grammarly OA 面试真题解析：多人协作文档系统设计

Design a system that allows multiple users to collaborate on a document.

Description

For MVP, focus on:

• Defining back-end APIs for interaction between client and server.
• Defining the document storage layer.
• Explaining how edits are propagated to other users and how changes are rendered on the client side.

After MVP:

• Enhance the design to support millions of documents.
• Identify and fix bottlenecks that affect scaling.

这道题要求设计一个多人实时协作文档系统，核心要先把 MVP 讲清楚：前端如何通过 API 与后端交互，文档如何存储，以及一位用户的编辑如何及时传播给其他在线用户并在客户端正确渲染。回答时通常要围绕文档模型、版本控制、变更同步机制、冲突处理以及实时推送来展开；进阶部分再讨论如何把系统扩展到百万级文档与高并发用户，包括分片、缓存、消息队列和热点文档的性能瓶颈分析。