Redis · Ops · Building an internal platform with redis-ops from scratch: architecture and decision log

150
REr/redis-ops·posted by winter·just nowAnnouncement

Building an internal platform with redis-ops from scratch: architecture and decision log

Most redis-ops articles stop at "how to use it" and never cover "when not to use it". This is an attempt at the second half.

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.

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.

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75 comments

75 comments

M
NnikicOP·2 days ago

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

501
WwinterMod·just now

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

480
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.

171
Cchen_dev·28 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.

326
Bbob_chen·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.

104
Hhuang_keMod·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.

59
Rran_bo·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.

406
Mmike_xu·2 days agoLevel 6

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

255
Hhuang_keOP·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.

12
Sswoole_leeOP·1 hour agoedited

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

1
Zzhou_yi·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.

44
Llinlin·2 days ago

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

304
Rrase·2 days ago

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

32
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.

218
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.

209
Rrase·2 days 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.

178
Oops_wang·3 minutes ago

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

84
Wwinter·2 hours ago

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

463
Cchen_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.

454
Bbob_chen·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.

420
Nnikic·yesterday

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.

414
Sslow_query·5 hours ago

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

395
Wwinter·2 days agoedited

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

230
Zzhu_zong·2 days ago

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

349
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.

228
Oops_wang·2 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.

335
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.

308
Hhuang_ke·2 days ago

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

438
Ddev_zhouOP·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.

10
Oops_wang·2 days ago

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

9
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.

251
Rran_bo·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.

278
Wwinter·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.

257
Mmike_xu·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.

213
Nnikic·yesterdayedited

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

51
Hhuang_keMod·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.

183
Aalice_dev·2 hours ago

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

183
Oops_wang·12 minutes 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.

179
Hhuang_ke·2 days ago

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

162
Ttang_hao·2 days ago

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

17
Ddev_zhouOP·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.

431
Kkernel_panicOP·just now

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.

95
Lli_ming·5 hours agoedited

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

83
Lli_ming·2 days agoedited

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

71
Aalice_dev·2 days ago

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

61
Ttang_haoOP·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.

1
Oops_wang·5 hours ago

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

58
Zzhu_zong·28 minutes ago

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

57
LlinlinOP·1 hour 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.

161
Aalice_dev·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.

94
Rran_boOP·12 minutes ago

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

76
Kkernel_panic·yesterday

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.

1
Cchen_devOP·28 minutes ago

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

23
Aalice_dev·28 minutes agoedited

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

35
Ttang_hao·2 days ago

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

55
Sslow_query·2 days ago

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

43
Sswoole_lee·3 minutes ago

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

60
Sswoole_lee·3 minutes ago

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

37
Hhuang_ke·2 days ago

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

15
Zzhou_yiOP·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.

447
Hhuang_ke·2 days ago

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

333
Mmike_xu·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.

278
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.

159
Hhuang_ke·5 hours ago

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

7
Bbob_chen·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.

327
Sslow_query·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.

104
Kkite·5 hours 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.

132
Aalice_dev·28 minutes ago

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

6
Bbob_chen·2 hours 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.

1
Oops_wang·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.

69
Llinlin·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
Hhuang_keOP·2 days agoedited

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

3
Kkernel_panicOP·just now

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

1
Zzhu_zong·5 hours 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.

5
Aalice_dev·2 days ago

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

1

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