Tableau · Code review · Cut our tableau-review build from 4 minutes to 40 seconds with these 5 changes

173
TAr/tableau-review·posted by alice_dev·3 hours agoExperience

Cut our tableau-review build from 4 minutes to 40 seconds with these 5 changes

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.

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".

# Load test: do not jump straight to the max concurrency.
# Ramp it up, otherwise you miss the knee.
for c in 50 100 200 400 800; do
  wrk -t8 -c$c -d60s --latency http://127.0.0.1:8080/api/feed
  sleep 20
done

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.

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.

94 comments

94 comments

M
Cchen_dev·2 days ago

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

502
Oops_wang·2 days ago

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

499
Cchen_dev·28 minutes ago

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

428
Lli_ming·2 days ago

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

350
Bbob_chen·2 days ago

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

144
Nnikic·yesterdayedited

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

376
Zzhu_zong·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.

142
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.

346
Ddev_zhou·2 days ago

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

42
Rran_bo·28 minutes ago

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

78
Cchen_dev·3 minutes ago

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

393
Hhuang_ke·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.

507
RraseOP·2 days ago

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

3
Sslow_query·5 hours agoLevel 6

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

45
Ddev_zhou·2 days ago

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

53
Wwinter·28 minutes agoLevel 6

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

4
Bbob_chen·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.

370
Ttang_hao·28 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.

52
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.

34
Cchen_dev·28 minutes ago

One counter-example: below tableau-review 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·1 hour ago

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

96
Zzhu_zong·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.

22
Lli_ming·2 days ago

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

1
Zzhu_zong·2 days ago

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

1
Kkernel_panic·2 days agoedited

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

267
Zzhou_yiOP·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.

297
Mmike_xu·2 days ago

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

333
Llinlin·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.

326
Kkite·2 days ago

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

345
Aalice_dev·2 days ago

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

1
Cchen_devOP·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.

199
Rrase·1 hour 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.

226
Wwinter·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.

455
Mmike_xu·12 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.

502
Mmike_xu·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.

406
Zzhou_yi·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.

28
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.

233
Kkite·just now

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

160
Zzhu_zong·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.

72
Ttang_haoOP·1 hour ago

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

138
Bbob_chen·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.

441
Lli_mingMod·2 days ago

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

187
Hhuang_keOP·just now

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

104
Oops_wangMod·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.

301
Sswoole_lee·yesterdayedited

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.

429
Llinlin·12 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.

220
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.

118
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.

70
Aalice_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.

18
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.

15
Zzhu_zong·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.

175
Sslow_query·yesterdayedited

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.

242
Sswoole_lee·2 days ago

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

488
Cchen_devOP·yesterday

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

385
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.

6
Zzhu_zong·2 days agoedited

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.

117
Bbob_chen·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.

5
WwinterOP·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.

93
Bbob_chen·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.

151
Sslow_query·2 days agoedited

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

126
Nnikic·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.

116
Oops_wang·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.

116
Sslow_query·2 days ago

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

65
Lli_ming·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.

99
Rran_boOP·2 days ago

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

22
Ddev_zhouOP·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.

9
Lli_ming·2 days ago

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

57
Cchen_dev·1 hour ago

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

54
Ttang_haoOP·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.

322
Oops_wang·3 minutes ago

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

21
Oops_wangOP·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.

65
Ttang_hao·3 minutes ago

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

24
Zzhou_yi·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.

48
Rran_bo·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.

38
Zzhou_yi·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.

37
Cchen_dev·1 hour ago

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

24
Rrase·2 days ago

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

23
Llinlin·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.

19
Oops_wang·12 minutes ago

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

17
Ddev_zhou·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
Oops_wang·2 days ago

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

215
Nnikic·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.

174
Llinlin·2 days ago

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

258
Zzhou_yi·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.

11
Wwinter·2 days ago

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

9
Wwinter·2 days ago

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

1
Zzhu_zong·2 days ago

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

2
Sslow_query·2 days ago

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

8
Kkite·2 days agoedited

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.

5
Bbob_chen·2 days ago

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

5
Bbob_chen·12 minutes ago

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

2
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.

1
Sswoole_lee·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.

1
Wwinter·2 days ago

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

1

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