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Debugging Testing and Optimization Questions

Core engineering skills for identifying, diagnosing, testing, and improving code correctness and performance. Covers approaches to finding and fixing bugs including reproducible test case construction, logging, interactive debugging, step through debugging, and root cause analysis. Includes testing strategies such as unit testing, integration testing, regression testing, test driven development, and designing tests for edge cases, boundary conditions, and negative scenarios. Describes performance optimization techniques including algorithmic improvements, data structure selection, reducing time and space complexity, memoization, avoiding unnecessary work, and parallelism considerations. Also covers measurement and verification methods such as benchmarking, profiling, complexity analysis, and trade off evaluation to ensure optimizations preserve correctness and maintainability.

EasyTechnical
0 practiced
Describe how static analysis and linters can catch bugs before runtime. Give examples of issues caught by static tools versus those that require dynamic tests. For a typed language like TypeScript, mention type-driven checks you rely on.
HardTechnical
0 practiced
A distributed system intermittently returns stale data due to caching layers. Walk through how to debug the issue, from reproducing to root cause, including cache TTL, eventual consistency, stale reads, and race conditions in cache invalidation.
HardTechnical
0 practiced
Design a small experiment to compare the energy consumption (power usage) of two implementations of a tight computation loop (e.g., image filter) and explain why energy might differ even with similar CPU usage. Mention measurement tools and controlled variables.
MediumTechnical
0 practiced
A backend service uses an in-memory cache that sometimes grows until the process is OOM-killed. Describe strategies to prevent unbounded memory growth, including cache eviction policies, memory-aware caching, backpressure, and monitoring. Provide sample guard thresholds and alerting ideas.
HardTechnical
0 practiced
Write a short Java method that demonstrates a deadlock between two threads using synchronized blocks. Then propose two code-level fixes and describe runtime checks or tests to detect deadlocks in CI.

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