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LetsGit.IT/Categories/Spring
Springhard

How does `@Async` work in Spring and what’s a common gotcha?

Tags
#async#executor#proxy#spring
Back to categoryPractice quiz

Answer

Spring runs the method on a separate executor via a proxy. A common gotcha is self-invocation (calling the method from the same class) which bypasses the proxy, so it won’t run async. Also remember to size the executor.

Advanced answer

Deep dive

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

  • Context (tags): async, executor, proxy, spring
  • Lifecycle: what happens at runtime (render/build, request/response, background jobs).
  • Caching: where cache lives, cache keys, how to invalidate without chaos.
  • Security: authn/authz, secrets, attack surface (SSRF/CSRF).
  • 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-does-`@async`-work-in-spring-and-what’s-a-co"
function explain() {
  // Start from the core idea:
  // Spring runs the method on a separate executor via a proxy. A common gotcha is self-invocat
}

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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