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Open Source · Blog · Built a visual debugging panel for open-source-blog over the weekend

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OSr/open-source-blog·posted by swoole_lee·6 hours agoTutorial

Built a visual debugging panel for open-source-blog over the weekend

Short version: open-source-blog 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.

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 open-source-blog itself but our upstream connection reuse — the load test traffic was too clean and hid the long-tail requests.

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10 comments

10 comments

M
Sswoole_lee·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.

482
Oops_wang·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.

324
Sswoole_leeOP·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.

141
Rrase·12 minutes ago

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

95
Ddev_zhou·3 minutes ago

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

2
Aalice_dev·5 hours ago

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

441
Rran_bo·yesterday

One counter-example: below open-source-blog 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
Mmike_xu·2 hours ago

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

354
Llinlin·28 minutes agoedited

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

2
Wwinter·12 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.

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