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Keyboard Community · I built a small tool with keyboard — code is open, feedback welcome

38
KEr/keyboard·posted by tang_hao·2 hours agoDiscussion

I built a small tool with keyboard — code is open, feedback welcome

It took me two weeks of on-and-off digging and plenty of wrong turns. Writing the process down as it happened so the next person spends less time.

We also fixed monitoring along the way: replaced average-based alerts with percentiles and split them per endpoint. False alerts dropped by about seventy percent and the on-call rotation visibly cheered up.

Performance44%
Maintainability28%
Ecosystem and community17%
Hiring difficulty11%

65 votes total

12 comments

12 comments

M
Zzhu_zong·yesterday

One counter-example: below keyboard 7.4 the semantics of that code are different, so do not copy it verbatim. We got burned in staging and rolled back once.

439
Ddev_zhou·2 days ago

I just read the keyboard source — the author actually explains the reasoning in a comment, roughly "so that it degrades into predictable behaviour in extreme cases".

15
Hhuang_ke·12 minutes ago

Sharing our numbers, 8 cores 16GB, same scenario:

| Concurrency | P50 | P99 |
|---|---|---|
| 200 | 12ms | 88ms |
| 500 | 31ms | 340ms |

P99 clearly collapses at 500 concurrency, which lines up with your knee point.

398
Sslow_query·3 minutes agoedited

Worth learning from this debugging approach. We went straight at the logs and took a much longer route.

503
Sslow_query·2 hours ago

A question: what changes in a container with a 512Mi memory limit? That is how we run it in production.

20
Zzhou_yi·1 hour ago

There is actually a simpler fix that needs no architecture change: move this check up to the gateway and the problem disappears. The cost is one extra lookup at the gateway.

252
Nnikic·12 minutes agoedited

This matches what we see in production. We only hit it past 3k QPS; the earlier load tests showed nothing — the test traffic was too clean, with no long-tail requests.

383
Aalice_dev·just now

Saved. I am reworking this area this week — this saves a lot of wrong turns.

19
Rran_bo·1 hour ago

Agreeing with the above. One addition: with this option enabled the GC count in your metrics doubles, so adjust the alert threshold at the same time or it will keep firing.

243
Rran_bo·5 hours ago

Has anyone run a controlled experiment? I did, reducing it to a single variable, and the difference was 4% — within noise. So I suspect the main cause is something else.

10
Bbob_chen·12 minutes ago

We have run this in production for two years without hitting it. That said, we never reached this scale, so our experience is not really evidence here.

470
Kkernel_panic·just now

This is not a keyboard problem, it is a usage problem. The docs say this API is not thread-safe and you must lock around it yourself.

12

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