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Edge Computing · Resources · The edge-computing-resources execution flow in one diagram (with sequence chart)

52
ECr/edge-computing-resources·posted by rase·1 hour agoOpen source

The edge-computing-resources execution flow in one diagram (with sequence chart)

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

What genuinely surprised me was the tail. The average looked great while P99 jumped by an order of magnitude past some threshold. The cause was not edge-computing-resources itself but our upstream connection reuse — the load test traffic was too clean and hid the long-tail requests.

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".

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26 comments

26 comments

M
Oops_wang·just now

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

471
Ttang_hao·12 minutes agoedited

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

426
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.

91
Nnikic·1 hour ago

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

425
Cchen_dev·2 days ago

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

82
Sswoole_lee·2 days 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.

291
Rran_boOP·just now

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

229
Cchen_devOP·3 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.

213
Rrase·yesterday

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

436
Rrase·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.

279
Kkernel_panic·just now

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.

260
Kkite·3 minutes ago

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

115
Ttang_hao·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.

358
Ddev_zhou·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.

13
Ttang_hao·2 days ago

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

346
Hhuang_ke·5 hours ago

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

34
Aalice_dev·1 hour agoedited

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

152
KkiteOP·2 days ago

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

22
Oops_wang·2 days ago

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

27
Sslow_queryOP·2 days 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.

2
Hhuang_ke·3 minutes 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.

372
Wwinter·3 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.

6
Sslow_query·2 hours ago

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

489
Ttang_haoMod·12 minutes agoedited

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

1
Rran_bo·1 hour 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.

13
Wwinter·2 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.

1

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