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PHP Community · Open-sourced a rate-limiting middleware for PHP with token bucket and sliding window

20
phpr/php·posted by alice_dev·2 days agoExperience

Open-sourced a rate-limiting middleware for PHP with token bucket and sliding window

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.

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.

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13 comments

13 comments

M
Cchen_dev·3 minutes ago

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

305
Ddev_zhou·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.

359
WwinterOP·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.

176
Sslow_queryMod·28 minutes ago

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

224
Kkernel_panicMod·1 hour ago

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

382
Kkite·2 days ago

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

217
Hhuang_ke·just now

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

162
Ttang_hao·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.

161
Hhuang_ke·just now

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

122
Hhuang_keOP·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.

349
Oops_wang·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.

113
Ttang_hao·12 minutes agoedited

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.

135
Sswoole_lee·28 minutes ago

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

37

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