Implement a Rate Limiter
Last updated: February 21, 2025
Quick Overview
Design and implement a rate limiter that restricts the number of requests a client can make within a given time window.
Rivian
February 21, 20259
5
2,462 solved
Design and implement a rate limiter that restricts the number of requests a client can make within a given time window.
Rate limiting is critical in Rivian's cloud APIs that serve millions of vehicles. Each vehicle polls for updates, reports telemetry, and syncs state. Without rate limiting, a misbehaving vehicle software version could overwhelm backend services. This tests practical systems coding.
What the Interviewer Expects
- Implement at least one rate limiting algorithm (sliding window, token bucket, or fixed window)
- Handle concurrent requests correctly with proper synchronization discussion
- Support configurable rate limits per client
- Write clean, well-tested code with clear API design
- Discuss tradeoffs between different rate limiting algorithms
Key Topics to Cover
How to Approach This
- Clarify input constraints and edge cases before writing code.
- Walk through your approach verbally and confirm with the interviewer before coding.
- Start with a brute force solution, then optimize. Mention time and space complexity.
- Test your solution with examples, including edge cases like empty input or duplicates.
- Consider common patterns: sliding window, two pointers, hash map, BFS/DFS, dynamic programming.
Possible Follow-up Questions
- How would you implement this in a distributed system with multiple servers?
- What are the tradeoffs between token bucket and sliding window approaches?
- How would you handle rate limit responses gracefully for vehicle clients?
- How would you implement different rate limits for different API endpoints?
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Practice DSA ProblemsSample Answer
Problem Analysis
In this problem, we need to implement a rate limiter to restrict the number of requests a client can make within a specified time window. The sliding window algorithm is particularly applicable here b...
Approach
- Data Structure: Use a dictionary to map client IDs to a list of timestamps representing when each request was made.
- Request Handling: For each incoming request, we'll do the following: ...
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