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Llamaindex · Toolchain · Those easily-missed type details in llamaindex-tools

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LLr/llamaindex-tools·posted by dev_zhou·yesterdayHelpPinned

Those easily-missed type details in llamaindex-tools

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

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".

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.

What genuinely surprised me was the tail. The average looked great while P99 jumped by an order of magnitude past some threshold. The cause was not llamaindex-tools itself but our upstream connection reuse — the load test traffic was too clean and hid the long-tail requests.

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.

555 comments

555 comments

· first 120 loaded
M
Rran_boOP·2 days ago

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

470
Cchen_dev·2 days ago

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

512
Sslow_query·28 minutes ago

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

214
Rrase·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.

187
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.

4
Kkernel_panic·2 hours ago

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

439
Nnikic·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.

423
Nnikic·2 days ago

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

417
Cchen_dev·2 days ago

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

392
Ttang_hao·2 days ago

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

373
Sslow_query·2 days ago

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

372
Aalice_dev·2 days agoedited

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

191
Kkernel_panic·2 days ago

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

117
Mmike_xuOP·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.

83
Sslow_queryOP·2 days ago

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

306
Aalice_dev·2 days ago

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

277
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.

274
Zzhou_yi·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.

257
Aalice_devOP·28 minutes agoedited

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

15
Hhuang_keOP·2 days ago

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

47
Sswoole_lee·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.

172
Mmike_xu·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.

4
Mmike_xu·5 hours 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 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.

161
Ddev_zhou·just now

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

28
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.

17
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.

418
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.

261
Zzhu_zong·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.

263
Kkernel_panic·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.

23
Mmike_xu·2 days agoLevel 6

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.

2
Kkite·2 days ago

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

50
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.

482
Kkite·2 days ago

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

21
Nnikic·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.

4
Zzhou_yi·2 days ago

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

286
Sslow_query·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.

249
Mmike_xu·12 minutes ago

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

225
Nnikic·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.

335
Kkernel_panic·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.

205
Nnikic·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.

202
Rrase·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.

200
NnikicOP·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.

494
Bbob_chenOP·12 minutes ago

One counter-example: below llamaindex-tools 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
Hhuang_ke·2 days ago

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

401
Llinlin·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.

1
Nnikic·2 days ago

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

30
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.

25
Lli_ming·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.

30
Cchen_devOP·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.

175
Kkernel_panic·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·12 minutes 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.

160
Sslow_query·2 days ago

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

106
Mmike_xu·yesterday

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

101
Aalice_dev·2 days ago

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

248
RraseOP·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
Mmike_xuOP·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.

155
Ttang_hao·3 minutes ago

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

100
RraseOP·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.

39
Lli_ming·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.

404
Cchen_dev·2 days ago

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

59
Kkite·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.

319
Ddev_zhou·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_devOP·2 days ago

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

163
Mmike_xuOP·2 days ago

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

5
Nnikic·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.

216
Rran_bo·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.

318
Cchen_dev·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.

198
LlinlinOP·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.

266
Zzhou_yi·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.

53
Rran_boOP·2 days agoLevel 6

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

79
Oops_wang·yesterday

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.

167
Mmike_xu·2 days ago

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

124
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.

86
Llinlin·2 days ago

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

281
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.

224
Sslow_queryMod·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.

83
Oops_wang·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.

119
Rran_bo·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.

42
Zzhou_yi·2 days ago

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

67
Bbob_chen·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.

63
Lli_ming·2 days ago

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

60
Ddev_zhou·just now

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.

57
Nnikic·5 hours ago

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

44
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.

36
Ddev_zhou·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.

27
Zzhu_zong·2 days agoedited

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

25
Mmike_xu·2 days ago

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

18
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.

20
Zzhu_zong·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.

91
Nnikic·2 days ago

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

20
Rrase·2 days ago

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

13
Zzhou_yi·2 days ago

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

442
Llinlin·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.

343
Ddev_zhouMod·12 minutes ago

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

13
Kkernel_panic·2 days ago

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

9
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.

7
Bbob_chen·12 minutes ago

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

38
Oops_wang·2 days agoedited

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

6
Rran_bo·2 days ago

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

5
Hhuang_ke·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.

5
Nnikic·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.

113
Aalice_dev·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
Rran_bo·just nowedited

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
Ttang_hao·yesterday

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.

452
Aalice_dev·12 minutes ago

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

223
Ttang_hao·yesterday

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

292
Sslow_queryOPMod·2 days ago

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

81
Aalice_devMod·12 minutes agoLevel 6

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

97
Cchen_dev·2 days agoedited

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

138
Zzhu_zong·2 days ago

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

19
Nnikic·2 days agoLevel 6

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

1
Mmike_xu·2 days agoedited

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

65
Aalice_devOP·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.

2
Aalice_dev·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.

41
NnikicMod·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.

231
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.

96
Aalice_dev·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.

12
Lli_ming·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.

1
Hhuang_ke·1 hour ago

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

1

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