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App Design · News · The edge cases the app-design-news docs never spell out

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ADr/app-design-news·posted by linlin·3 days agoInternalsLocked

The edge cases the app-design-news docs never spell out

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.

One last trap: in container environments remember to adjust the memory-related parameters in step. Otherwise the host limit and the process expectation disagree, and the symptom is intermittent, unreproducible failure.

On trade-offs, my view is this: if nobody on the team owns this area long-term, do not introduce a second mechanism. With two coexistence you first have to work out which one is even in play when things break, and that costs far more than the performance you saved.

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7 comments

7 comments

M
Aalice_dev·just now

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.

376
Kkernel_panic·28 minutes ago

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

93
Wwinter·28 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.

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Sslow_query·1 hour ago

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

476
Hhuang_ke·just now

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.

25
Cchen_dev·12 minutes 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.

9
Oops_wang·2 hours ago

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

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