Covers writing clean, maintainable, and readable code together with proactive techniques to prevent failures and handle unexpected inputs. Topics include naming and structure, modular design, consistent style, comments and documentation, and making code testable and observable. Defensive practices include explicit input validation, boundary checks, null and error handling, assertions, graceful degradation, resource management, and clear error reporting. Candidates should demonstrate thinking through edge cases such as empty inputs, single element cases, duplicates, very large inputs, integer overflow and underflow, null pointers, timeouts, race conditions, buffer overflows in system or embedded contexts, and other hardware specific failures. Also evaluate use of static analysis, linters, unit tests, fuzzing, property based tests, code reviews, logging and monitoring to detect and prevent defects, and tradeoffs between robustness and performance.
MediumTechnical
26 practiced
Discuss trade-offs between adding defensive checks and maintaining high performance in a high-throughput network service. List three defensive guards that add noticeable cost (e.g., deep validation, heavy logging, copying buffers) and propose specific mitigations to retain safety while reducing performance impact.
HardTechnical
22 practiced
Analyze trade-offs between performing aggressive defensive validation at service boundaries versus pushing validation to client libraries. Consider performance, debugging, backward compatibility, developer experience, and operational burden. Provide concrete guidelines for when the service should be strict and when the client should be responsible.
HardSystem Design
29 practiced
Design a test and monitoring strategy to ensure a newly deployed Go binary will not cause memory or goroutine leaks at scale. Include static checks, unit/integration tests with pprof, CI thresholds, canary monitoring metrics (RSS, goroutine count), automatic rollback triggers, and post-deploy analysis steps with concrete thresholds.
HardTechnical
23 practiced
A critical open-source library has a known vulnerability that many services depend on. Some services can be patched quickly; others cannot. As an SRE lead, present a remediation plan that balances speed and coverage: include temporary runtime mitigations, prioritized rollout list, communication strategy, rollback plan, and long-term approach to avoid similar widespread dependency risks.
HardTechnical
22 practiced
Implement a safe file upload handler in Java (pseudocode acceptable) that: validates file type using magic numbers, enforces a maximum size without loading the whole file into memory, streams the upload to a temporary file, and guarantees temporary file cleanup even on exceptions. Show interfaces for unit testing the behavior.
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