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Offline First · Open source · Six rules for error handling in offline-first-opensource that I settled on

79
OFr/offline-first-opensource·posted by zhou_yi·yesterdayReview

Six rules for error handling in offline-first-opensource that I settled on

Some background first. Our setup is offline-first-opensource plus three downstream services, seven figures of daily requests, peaking around nine in the evening.

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.

Performance44%
Maintainability28%
Ecosystem and community17%
Hiring difficulty11%

134 votes total

39 comments

39 comments

M
Kkite·28 minutes ago

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

450
Zzhu_zongOP·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.

44
Bbob_chen·2 hours agoedited

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

1
Lli_ming·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.

266
Zzhu_zong·2 days ago

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

2
Kkernel_panic·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.

27
Hhuang_keOP·12 minutes ago

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

377
Cchen_dev·12 minutes ago

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

398
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.

370
NnikicOP·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.

283
Mmike_xu·3 minutes ago

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

473
Nnikic·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.

313
Mmike_xu·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.

1
Kkite·1 hour agoedited

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

461
WwinterOP·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.

61
Aalice_dev·5 hours ago

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

106
Llinlin·just nowLevel 6

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

32
Rran_bo·2 days agoLevel 6

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

12
Nnikic·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.

137
Nnikic·2 days ago

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

439
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.

18
Kkite·1 hour ago

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

363
Kkernel_panicOP·2 days ago

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

4
Ddev_zhou·2 days ago

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

343
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.

7
Cchen_dev·yesterday

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

213
Aalice_dev·2 hours ago

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

143
Mmike_xu·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.

83
RraseOP·3 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.

13
Hhuang_ke·3 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.

57
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.

47
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.

35
Ddev_zhou·2 days ago

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

2
Mmike_xu·12 minutes ago

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

8
Sswoole_lee·2 days ago

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

6
Wwinter·2 days ago

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

1
Lli_ming·12 minutes ago

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

1
Kkernel_panic·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.

1
Rran_bo·2 days ago

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

1

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