kacerrandClaude Fable 5
7219eb5a23
Includes solved 02-worker-pool and 09-safe-counter (mutex, atomic, sharded). Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01GbnJj9ZqEx9nUvzkjdwfMq
67 lines
3.0 KiB
Markdown
67 lines
3.0 KiB
Markdown
# Go SRE Interview Gym
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A monorepo of hands-on exercises covering what actually gets asked in Go
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live-coding rounds for SRE roles. Each numbered folder is self-contained:
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- `main.go` — the assignment (in comments) + a scaffold with TODOs and a small
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runnable demo
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- `main_test.go` — the interviewer: tests that define "correct", including the
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traps (goroutine leaks, races, boundary conditions)
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- `README.md` — the deep dive: why the idiom exists, what breaks in production,
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and the follow-up questions interviewers reach for
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## Setup
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Go ≥ 1.22 required (loop-variable semantics), any recent toolchain is fine —
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built and verified against **go 1.27**. Pure stdlib, zero dependencies.
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## Workflow
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```bash
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# pick an exercise, read the assignment in main.go, implement the TODOs
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go test -race ./01-url-health-checker/ # -race ALWAYS. non-negotiable.
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# run everything you've solved so far
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go test -race ./...
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# some exercises have benchmarks worth exploring
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go test -bench=. -cpu=1,4,8 ./09-safe-counter/
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```
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Interview-realistic rules: timer set to 30 min, no autocomplete, no LSP if
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you're brave, and **narrate your reasoning out loud** — the talking is graded
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as much as the code.
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## The ladder
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| # | Exercise | Core skill | Freq in interviews |
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|---|----------|-----------|--------------------|
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| 01 | url-health-checker | bounded concurrency, ctx, HTTP hygiene | ★★★★★ |
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| 02 | worker-pool | channel closing protocol, WaitGroup | ★★★★★ |
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| 03 | rate-limiter | lazy state, mutex, monotonic time | ★★★★☆ |
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| 04 | log-topn | streaming, Scanner limits, map→sort | ★★★★☆ |
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| 05 | lru-cache | map+list composite, O(1) design | ★★★★☆ |
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| 06 | retry-backoff | jitter, ctx-aware sleep, error classes | ★★★☆☆ |
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| 07 | fan-in | leak-free cancellation, nil-channel trick | ★★★☆☆ |
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| 08 | graceful-shutdown | signals, Shutdown ctx inversion, k8s | ★★★☆☆ |
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| 09 | safe-counter | mutex vs atomic vs sharding, -race | ★★★★☆ (as warm-up) |
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| 10 | gotchas | "what does this print" trivia round | ★★★★★ |
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Suggested order: 09 → 02 → 01 → 03 → 05 → 04 → 06 → 07 → 08, with gotchas (10)
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sprinkled daily. 09 first because it calibrates you on `-race`; 01/02 are the
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highest-yield; 08 is the best *conversation* generator in on-sites.
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## Ground rules baked into the tests
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- Tests use timeouts to catch deadlocks and missing `close()` — a hanging test
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is a failing test with extra steps.
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- Several tests count goroutines or track peak concurrency with atomics —
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read them after solving; test-writing techniques are interview material too.
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- Everything must pass under `-race`. A green test that fails `-race` is red.
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## Note on the gotchas folder
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`10-gotchas/*` are predict-then-run programs: ex02 deadlocks on purpose, ex11
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doesn't compile on purpose. Run them individually (`go run ./10-gotchas/ex01-loopvar/`),
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not as part of `go build ./...`. Answers are collapsed in `10-gotchas/README.md`.
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