Kacam.net

Interview drills

进程和线程的区别

「进程是资源分配的最小单位,线程是 CPU 调度的最小单位」—— 然后呢?

Copy the prompt, then pick a model. It plays the interviewer and asks you through it scene by scene instead of handing you the answer.

On a phone with the app installed, the system opens the app directly. Links cannot open external apps inside WeChat — open it in a browser first.

The copied text ends with the answer key the model grades you against. Don't read it yourself first — working it out on your own is the point.

这一句几乎所有人都背得出来,所以真正的面试不会停在这里。这一份从那句话往下走:你说的「资源」具体是哪几样,哪几样其实没有共享;说「线程更轻量」,那轻多少、轻在哪一步上。

第三幕开始逼数字:创建一个、切换一次,各是什么量级。说得出结论、说不出数字的,它一律记成背的。

最后一幕会让你掐 60 秒重讲一遍,和开场那版并排比 —— 面试现场要交付的从来不是「我懂」,是一段说得出口的话。

★★★☆☆ · about 45 min · Tests: 共享了哪几张表、创建与切换的数量级、多进程还是多线程

What this one leans on

Concurrency and locks Scheduling and switching Memory and objects

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How to use this

This set interrogates rather than teaches. It is a mock interview: running out of answers is a normal outcome, and it will not cover for you or finish your sentence when you trail off. If you want to understand a topic rather than rehearse for an interview, go to Computer systems, Databases or Algorithms — those guide you instead.

How one stock question fills forty minutes: the five-layer ladder

  • L1 · Definition — what each term means, list the differences. Can't answer: you never learned it.
  • L2 · Mechanism — which structure, which step actually produces that difference. Can't answer: you memorised the conclusion only.
  • L3 · Numbers — by how much? How many microseconds, how many times, how many I/Os. Can't answer: you've never done it hands-on.
  • L4 · Choice — given a concrete scenario, which one, at what cost, and when is that choice wrong. Can't answer: you can't apply it.
  • L5 · Limits — under what conditions does everything you just said stop holding. Can't answer: you know it all, but you don't really understand it.

The bar: L4 is what passes an interview, L5 is what counts as really understanding it, and anything that stops at L1 is recorded as memorised.

Six scenes — the first and last are unique to this set

  • In scene one it does not interrupt, comment or hint. You deliver the version you already have, start to finish, and it records that as your baseline. The silence is deliberate — it is listening, it just isn't correcting you yet.
  • The middle four scenes work down the ladder; scene three, mechanism and numbers, is the main battleground.
  • The last scene puts sixty seconds on the clock and makes you deliver it again, side by side with your opening version — because what an interview asks you to hand over isn't "I understand it", it's a sentence you can actually say out loud.

How to start

  1. Pick one, open it, copy the prompt.
  2. Paste it into a brand-new conversation, say nothing, and wait for its first question.
  3. Then answer like you would in an interview: deliver your memorised version in one go. It's fine if it's rough — that's the baseline it compares against at the end.
  4. After that it starts pressing. Running out of answers is a normal outcome: this isn't study material, it's a mock interview.

Five commands you can call out at any time

  • 跳过 move to the next scene now
  • 提示 give me a hint, not the answer
  • 直说吧 spell the full answer out
  • 重讲 jump straight to the last scene, re-record the sixty-second version and compare it with the opening one
  • 复盘 jump to the wrap-up and print the review card

Three traps

  • The prompt you copy has the answer key at the end — don't read it first. One of its columns is the "recital fingerprints": the exact sentences you're most likely to blurt out. Read them and there's nothing left to drill.
  • Don't hand over adjectives where a number belongs. "Much faster", "barely any overhead" — it stops you and asks for the figure. A conclusion you can't put an order of magnitude on is recorded as memorised.
  • The last two groups are language-bound: do the Java group if you write Java, the Go group if you write Go. They are not translations of each other — each picks its own questions — so there's no need to do both.

Interviewing for a backend role next week? Take process versus thread, TCP versus UDP, why B+ trees, isolation levels, the three cache failure modes, and idempotency — the six most frequent, with almost no overlap. Been hammered in interviews and want to find the gaps? Start with "from URL to rendered page": it exposes every weak spot horizontally, and you can pick your next ones from what it turns up.