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Optimization and Technical Trade Offs Questions

Focuses on evaluating and improving solutions with attention to trade offs between performance, resource usage, simplicity, and reliability. Topics include analyzing time complexity and space complexity, choosing algorithms and data structures with appropriate trade offs, profiling and measuring real bottlenecks, deciding when micro optimizations are worthwhile versus algorithmic changes, and explaining why a less optimal brute force approach may be acceptable in certain contexts. Also cover maintainability versus performance, concurrency and latency trade offs, and cost implications of optimization decisions. Candidates should justify choices with empirical evidence and consider incremental and safe optimization strategies.

MediumTechnical
53 practiced
Given a high-volume log stream that cannot fit in memory, implement a memory-efficient streaming aggregator in Python or pseudocode that computes per-key counts and top-k keys periodically. Discuss memory-accuracy trade-offs and how to handle heavily skewed key distributions.
MediumTechnical
45 practiced
Describe how you would use Linux perf, flamegraphs, and eBPF tools to diagnose kernel-level and user-space bottlenecks in a high-throughput web server. Explain setup for production-safe collection, sampling intervals, overhead trade-offs, and how to correlate kernel and user-space findings.
MediumTechnical
48 practiced
Tail latency for an API endpoint has increased after a deployment. Describe a step-by-step investigation plan: which metrics to examine (latency percentiles, CPU, GC, queue lengths), how to sample and profile, how to use tracing to find problematic spans, and what quick mitigations to test before rolling back. Explain how you'd validate root cause before a full rollback.
MediumTechnical
56 practiced
Your autoscaling group is thrashing: instances scale up immediately under burst then scale down, causing oscillation and cost spikes. Diagnose likely causes (sensitive thresholds, slow scale-up, short bursts) and propose robust scaling policies and architectural mitigations that balance cost and reliability.
EasyTechnical
46 practiced
Implement a thread-unsafe LRU cache in Python with O(1) get and put operations. Your class should support: constructor(capacity), get(key) -> value or -1, put(key, value). Evict the least recently used item when capacity is exceeded. Include example usage and explain the time/space trade-offs of your implementation.

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