Overview
What this challenge is about.
Build a thread-safe LRU cache with TTL eviction and single-flight dedup in Java or Go, then submit your design doc and benchmark report for a verifiable certificate.
The scenario
The SaaS (recently hit a stale-cache incident that cost a customer's checkout flow for 22 minutes) has elevated cache correctness to a CTO-tracked metric.
The Brief
What you'll do, and what you'll demonstrate.
Design and implement a race-free LRU cache with single-flight loads and documented consistency, then validate against torn-read tests under heavy concurrency.
Earning criteria — what you'll demonstrate
- Apply read-write locks or copy-on-write idioms to a real cache
- Implement single-flight load deduplication correctly
- Document a consistency model precisely enough that other engineers can rely on it
- Test for torn reads under heavy concurrent load
Program Fit
Where this fits in your program.
Sharpens the same skills your degree expects you to demonstrate.
Concurrent and Parallel Programming
Bachelor · Systems
Strong alignment
This challenge maps to Concurrent and Parallel Programming at the Bachelor level. It sharpens the same practical skills your coursework expects — but in a real industry context with actual constraints and deliverables.
Skills
Skills you'll demonstrate.
Each one shows up on your verified credential.
- Concurrent Data Structures
Apply concurrent data structures to solve real industry problems and demonstrate production-level capability.
- Race Conditions
Apply race conditions to solve real industry problems and demonstrate production-level capability.
- Single Flight
Apply single flight to solve real industry problems and demonstrate production-level capability.
- Java
Apply java to solve real industry problems and demonstrate production-level capability.
- Benchmarking
Apply benchmarking to solve real industry problems and demonstrate production-level capability.
- Documentation
Apply documentation to solve real industry problems and demonstrate production-level capability.
Careers
Career paths this challenge builds toward
Completing this challenge demonstrates skills that transfer directly to these roles: