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Monitoring · Advanced · I upgraded our production monitoring-pro and hit these 11 landmines

58
MOr/monitoring-pro·posted by huang_ke·just nowDiscussion

I upgraded our production monitoring-pro and hit these 11 landmines

Short version: monitoring-pro 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.

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.

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27 comments

27 comments

M
Aalice_devOP·3 minutes ago

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

456
Ttang_hao·2 hours ago

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

69
Rrase·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.

480
Ddev_zhou·2 days ago

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

469
NnikicOP·5 hours 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.

362
Aalice_dev·2 days ago

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

344
Lli_ming·1 hour 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.

206
Sslow_query·5 hours 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.

22
Cchen_dev·2 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.

3
Sslow_queryOP·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.

397
Cchen_dev·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.

226
Wwinter·2 days ago

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

20
Ddev_zhou·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.

132
LlinlinOP·2 days ago

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

131
Wwinter·12 minutes ago

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

90
Nnikic·2 days agoedited

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.

1
Cchen_devOP·3 minutes ago

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

11
Lli_ming·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.

50
Wwinter·5 hours ago

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

41
Sslow_query·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.

316
Aalice_dev·28 minutes agoedited

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

116
Sslow_query·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.

112
Zzhou_yi·2 days ago

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

467
Aalice_dev·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.

238
Ddev_zhou·12 minutes ago

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

4
WwinterOP·5 hours ago

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

22
Ttang_hao·5 hours ago

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

1

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