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Offline First · Open source · Interview notes: how I answered a question about the offline-first-opensource concurrency model

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OFr/offline-first-opensource·posted by tang_hao·3 hours agoDiscussion

Interview notes: how I answered a question about the offline-first-opensource concurrency model

Short version: offline-first-opensource needs almost no tuning at small and medium scale — the point where it starts to hurt is much further out than most people assume. Full measurements below.

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.

Image placeholder · object storage in production
POST /api/uploads → CDN origin pull
2 comments

2 comments

M
Llinlin·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.

156
Ttang_haoOP·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.

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