Diagnose and Fix a Deadlock in a Multi-Threaded Payments Service
Overview
What this challenge is about.
Diagnose and Fix a Deadlock in a Multi-Threaded Payments Service. Intermediate challenge in code. Writing production code that solves real engineering proble...
The Brief
What you'll do, and what you'll demonstrate.
Reproduce, diagnose, and fix a production deadlock in a multi-threaded Java service; add a CI guardrail that prevents the regression.
This is not a coding exercise. It is the work a software engineer does between a Jira ticket and a merged PR. That distinction matters to every hiring manager who has seen candidates solve LeetCode problems and none who have shipped production code under real constraints.
When you finish, you will have something most graduates do not: a real-world deliverable, verified by Ewance, that you can show to a hiring manager and say "I did this. Here is the proof."
Earning criteria — what you'll demonstrate
- Read thread dumps to identify lock-ordering cycles
- Reproduce intermittent concurrency bugs reliably
- Choose between lock-ordering, lock-stripping, or lock-free fixes
- Build CI guardrails that catch regressions
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.
- Deadlock Analysis
Apply deadlock analysis to solve real industry problems and demonstrate production-level capability.
- Locks And Monitors
Apply locks and monitors to solve real industry problems and demonstrate production-level capability.
- Java
Apply java to solve real industry problems and demonstrate production-level capability.
- Threads
Apply threads 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.
- 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: