Vue · Remote · The edge cases the vue-remote docs never spell out

56
VUr/vue-remote·posted by kernel_panic·2 days agoPostmortem

The edge cases the vue-remote docs never spell out

Short version: vue-remote 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.

-- The query that broke: a full scan over 20M rows.
-- A composite index took P99 from 1.8s down to 42ms.
SELECT id, title, created_at
  FROM posts
 WHERE community_id = ?
   AND status = 1
 ORDER BY score DESC
 LIMIT 20;

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.

The first thing was to collapse the variables. We were changing config and upgrading the version at the same time, and afterwards nobody could say which change caused what. We rolled back to moving one variable at a time, re-ran three times, and only then did the curve settle. Tedious, but not skippable.

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.

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.

31 comments

31 comments

M
Mmike_xu·3 minutes agoedited

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

372
Hhuang_ke·2 days ago

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

361
Mmike_xu·yesterdayedited

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.

326
LlinlinOP·just nowedited

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.

125
Lli_ming·12 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.

150
Llinlin·2 days ago

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

314
Kkite·yesterday

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

444
Zzhu_zong·3 minutes ago

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

141
Bbob_chenOP·5 hours 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.

159
Cchen_dev·just nowedited

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

5
Aalice_dev·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.

5
Nnikic·2 days ago

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

2
Cchen_dev·1 hour ago

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

15
Ttang_haoOP·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.

445
Bbob_chenMod·2 days ago

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

2
Mmike_xu·2 days agoedited

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

125
Kkernel_panicOP·3 minutes ago

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

58
Oops_wang·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.

60
Ddev_zhou·just now

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

21
Zzhu_zong·5 hours ago

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

385
Zzhou_yi·3 minutes ago

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

328
Cchen_dev·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.

270
Nnikic·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.

266
Aalice_dev·just now

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.

251
Oops_wang·just nowedited

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

142
Sswoole_lee·28 minutes 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.

9
Lli_mingOP·1 hour ago

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

321
Cchen_dev·3 minutes ago

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

267
Zzhu_zong·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.

3
Rran_boMod·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.

1
Cchen_dev·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.

161

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