Modding · Reading list · Newbie question: how should a modding-books config file be organised?

766
MOr/modding-books·posted by winter·32 minutes agoPostmortem

Newbie question: how should a modding-books config file be organised?

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.

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.

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".

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.

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.

105 comments

105 comments

M
Wwinter·2 days ago

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

465
Zzhu_zong·2 days ago

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

47
Wwinter·2 days 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.

404
Hhuang_ke·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.

359
Ddev_zhou·just now

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

315
Ttang_hao·2 days 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.

291
Zzhu_zong·2 days ago

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

163
Oops_wang·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.

1
Ttang_hao·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.

287
Llinlin·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.

263
Mmike_xu·just now

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.

258
Mmike_xu·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.

259
Llinlin·just now

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

226
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.

178
Aalice_dev·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.

178
LlinlinOP·2 days agoedited

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

111
Ddev_zhou·2 days agoedited

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

170
Rran_bo·1 hour 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.

156
Kkernel_panic·2 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.

257
Zzhu_zong·2 days 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.

12
Sswoole_lee·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.

136
Oops_wang·2 days ago

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

95
Zzhou_yiOP·just now

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

22
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.

72
Ttang_hao·2 days ago

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

255
Zzhou_yi·2 days agoedited

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

63
Cchen_dev·2 days ago

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

3
Wwinter·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.

23
Zzhou_yi·2 days ago

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

68
Aalice_dev·3 minutes ago

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

20
Ttang_hao·2 days ago

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

54
Aalice_dev·12 minutes ago

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

53
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.

48
Sslow_query·2 days agoedited

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

45
Cchen_dev·28 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.

40
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.

358
Zzhou_yiOP·2 days ago

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

1
Kkernel_panic·2 days ago

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

188
Cchen_dev·2 days agoedited

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

7
Lli_ming·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.

51
Ddev_zhou·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.

74
Ttang_hao·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.

436
Rrase·2 days 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.

9
Zzhou_yi·2 days ago

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

159
Nnikic·2 days ago

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

92
Hhuang_ke·2 days ago

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

3
Lli_ming·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.

228
Sswoole_lee·2 days ago

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

152
Rran_bo·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.

257
Rrase·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.

132
NnikicOP·2 days agoLevel 6

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.

426
Cchen_devOP·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.

82
Mmike_xu·28 minutes agoedited

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

1
Ttang_hao·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.

75
Hhuang_ke·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.

106
Zzhu_zong·12 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.

74
Kkernel_panic·2 days agoedited

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

463
Sslow_queryOP·2 days agoLevel 6

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

198
Nnikic·3 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.

254
Rrase·2 days ago

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

202
Aalice_dev·just now

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.

177
Kkite·2 days agoLevel 6

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

457
Kkite·2 days agoLevel 6

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

200
Kkernel_panic·2 days ago

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

151
Sswoole_lee·2 days agoLevel 6

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.

173
Oops_wang·2 days agoLevel 6

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.

46
Cchen_dev·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.

10
Zzhu_zong·just now

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

1
RraseOP·just now

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.

3
Sswoole_lee·2 days 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.

35
Zzhu_zong·2 days agoedited

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

28
Aalice_dev·2 days agoedited

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.

2
Mmike_xu·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.

25
Sslow_query·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.

21
Sslow_query·2 days ago

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

423
Aalice_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.

8
Ttang_hao·1 hour agoedited

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

4
Hhuang_ke·2 days ago

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

14
Cchen_devOP·2 days agoedited

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.

35
Zzhou_yi·1 hour ago

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

3
Rran_bo·just now

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

2
Nnikic·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.

99
Rrase·2 days ago

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

2
Rran_bo·12 minutes ago

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

1
Sslow_query·28 minutes agoedited

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

4
Cchen_dev·28 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.

3
Ttang_haoMod·1 hour ago

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

435
Lli_ming·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.

368
Rrase·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.

233
Sswoole_lee·2 days ago

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

367
Zzhu_zong·2 days agoLevel 6

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

75
Ttang_hao·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.

44
Cchen_dev·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.

52
Rran_bo·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.

39
Zzhu_zong·2 days 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.

20
Kkite·2 days ago

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

71
Mmike_xuOP·2 days agoedited

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.

1
Nnikic·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.

1
Kkernel_panic·2 days ago

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

142
Aalice_dev·2 days ago

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

1
Lli_ming·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.

92
Llinlin·2 days 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.

26
Cchen_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.

14
Sswoole_lee·2 days ago

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

1
Cchen_dev·2 days 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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