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Tableau · Code review · War story: tableau-review timezone handling almost cost us a full day of billing

51
TAr/tableau-review·posted by zhu_zong·yesterdayDiscussion

War story: tableau-review timezone handling almost cost us a full day of billing

Short version: tableau-review needs almost no tuning at small and medium scale — the point where it starts to hurt is much further out than most people assume. Full measurements below.

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.

Documentation first44%
Source code first28%
Just ask someone17%
Run a demo and learn by error11%

87 votes total

19 comments

19 comments

M
Zzhou_yi·3 minutes ago

Thanks for sharing real numbers — far more useful than the articles that only cover concepts.

243
Rran_bo·2 hours ago

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

155
Wwinter·2 hours agoedited

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

147
Nnikic·1 hour ago

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

212
Sslow_query·2 days ago

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

192
Zzhou_yi·2 days 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.

45
Rrase·2 days 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.

26
Zzhu_zongOP·12 minutes agoedited

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.

50
Sswoole_lee·5 hours 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.

95
Kkite·28 minutes 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.

52
Rrase·2 days 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.

47
Ttang_hao·3 minutes ago

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

30
Sswoole_lee·28 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.

406
Kkernel_panic·2 days ago

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.

151
Zzhou_yi·2 days ago

Can you give a minimal reproduction? I ran it locally for ten minutes and could not reproduce on macOS with the latest version.

250
Sswoole_lee·2 days ago

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

323
Mmike_xu·yesterday

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.

4
Sslow_query·yesterday

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.

3
Rrase·3 minutes ago

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

2

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