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LetsGit.IT/Categories/Monoliths
Monolithshard

How do you refactor a messy monolith without stopping feature delivery?

Tags
#refactoring#incremental#testing#maintainability
Back to categoryPractice quiz

Answer

Work incrementally: pick one boundary, add tests around behavior, refactor behind stable interfaces, and ship in small steps. Use tech-debt budgeting and avoid big-bang rewrites.

Advanced answer

Deep dive

Expanding on the short answer — what usually matters in practice:

  • Context (tags): refactoring, incremental, testing, maintainability
  • Scaling: what scales horizontally vs vertically, where bottlenecks appear.
  • Reliability: retries/circuit breakers/idempotency, observability (logs/metrics/traces).
  • Evolution: keep changes cheap (boundaries, contracts, tests).
  • Explain the "why", not just the "what" (intuition + consequences).
  • Trade-offs: what you gain/lose (time, memory, complexity, risk).
  • Edge cases: empty inputs, large inputs, invalid inputs, concurrency.

Examples

A tiny example (an explanation template):

// Example: discuss trade-offs for "how-do-you-refactor-a-messy-monolith-without-sto"
function explain() {
  // Start from the core idea:
  // Work incrementally: pick one boundary, add tests around behavior, refactor behind stable i
}

Common pitfalls

  • Too generic: no concrete trade-offs or examples.
  • Mixing average-case and worst-case (e.g., complexity).
  • Ignoring constraints: memory, concurrency, network/disk costs.

Interview follow-ups

  • When would you choose an alternative and why?
  • What production issues show up and how do you diagnose them?
  • How would you test edge cases?

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