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CLI Tools · Career · The edge cases the cli-tools-career docs never spell out

91
CTr/cli-tools-career·posted by swoole_lee·2 hours agoAnnouncement

The edge cases the cli-tools-career docs never spell out

Some background first. Our setup is cli-tools-career plus three downstream services, seven figures of daily requests, peaking around nine in the evening.

Worth noting: the official docs do cover this, just in a very inconspicuous spot. I only found it reading the source comments, where the author explains the reasoning — roughly "so that it degrades into predictable behaviour in extreme cases".

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

155 votes total

23 comments

23 comments

M
Rrase·1 hour 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.

513
KkiteMod·2 hours agoedited

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.

451
Lli_ming·28 minutes ago

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

251
Rran_bo·1 hour agoedited

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.

344
Rran_bo·28 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.

53
Lli_ming·2 days ago

I see point 3 differently. The trade-off depends on your read/write ratio: read-heavy with little writing means caching actually widens the inconsistency window.

240
Rran_bo·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.

221
Rrase·just now

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

246
Aalice_dev·12 minutes ago

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

187
Kkite·3 minutes 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.

489
Kkite·2 hours agoedited

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

331
Kkernel_panic·3 minutes ago

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

1
Kkite·2 days ago

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

282
Sslow_query·just now

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

87
Zzhu_zong·2 days 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.

87
Cchen_dev·5 hours ago

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

75
Ddev_zhou·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.

73
Ttang_hao·1 hour agoedited

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.

49
Nnikic·2 days ago

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

38
Mmike_xu·2 days ago

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

99
Oops_wang·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.

23
Mmike_xu·1 hour ago

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

369
Rran_boOP·1 hour 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.

325

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