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Explain sync/async, Go concurrency, SQL vs NoSQL

ChimeSoftware Engineer · Technical Screen
EasySoftware EngineerTechnical ScreenSoftware Engineering Fundamentals

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This question evaluates understanding of execution models (synchronous vs asynchronous and blocking vs non-blocking), Go concurrency patterns (goroutines, channels versus shared-memory with locks), and database paradigms (SQL vs NoSQL) relevant to backend engineering.

You are interviewing for a backend engineering role. Answer the following conceptual questions clearly and with concrete examples.

1) Synchronous vs asynchronous

  • Define synchronous and asynchronous execution.
  • Explain how this differs from blocking vs non-blocking I/O.
  • Give an example of each in a backend service (e.g., handling HTTP requests, calling downstream services).

2) Go: channels vs shared-memory concurrency

  • Explain Go’s concurrency model at a high level (goroutines, scheduler).
  • Compare communicating via channels vs sharing memory with locks.
  • When would you prefer each approach? Call out common pitfalls (deadlocks, data races, goroutine leaks).

3) SQL vs NoSQL

  • Compare relational databases and common NoSQL types (key-value, document, wide-column).
  • Discuss trade-offs across:
  • data modeling and query patterns
  • transactions and consistency guarantees
  • scaling (vertical vs horizontal)
  • operational complexity
  • Provide a couple of example use cases where you would strongly prefer SQL, and where you would strongly prefer NoSQL.