Thomas Camlong
8f94ea47e3
Records where this stopped so it can be picked up cleanly:
1. c526dd2b7 (media-requests content-visibility) is typechecked but NOT measured - the
only performance claim on this branch not A/B'd before commit. Verify with
measure-board-paint.mts, three repeats; revert if image requests do not fall.
2. The one lever with headroom left is the tRPC router's eager integration imports - a
16.10 MiB subtree of 460 files reached by every API route, which pays twice because
both the ~41 MiB of retained source and the ~38 MiB of V8 compiler zones scale with
how much JavaScript the server compiles. Every allocator and V8-flag avenue is closed.
3. Deferred with prizes attached: ASCII-escaping bundles (9.45 MiB, needs its own PR),
lazy mysql2/pg (21.4 MiB, structurally blocked), beszelSystemStats chart SVG.
4. The proposed set for the clean PR, six changes producing -26% peak anon and -52% at
idle for +18% CPU - with the gRPC patch flagged as hygiene rather than a measured win,
and the +30% board-load figure flagged as not established.
50 lines
2.7 KiB
Markdown
50 lines
2.7 KiB
Markdown
# Homarr performance investigation
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Measured work on Homarr's memory and rendering cost, split by subject. Every figure here comes from
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a run of `scripts/benchmarks/stress-restore.mts` against a **restored real backup** — 4 boards, 51
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widgets, 11 integrations, driven through an actual login — not from a synthetic or empty container.
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| document | subject |
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| --- | --- |
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| [SERVER-MEMORY.md](./SERVER-MEMORY.md) | What the container's RAM is made of, and the changes that reduced it |
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| [CLIENT-PERFORMANCE.md](./CLIENT-PERFORMANCE.md) | Dashboard rendering cost in Chrome: DOM, fibers, images, paint |
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| [REJECTED.md](./REJECTED.md) | Ideas that were implemented and measured, then abandoned — with the numbers |
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| [METHODOLOGY.md](./METHODOLOGY.md) | The tools, and the measurement traps that produced wrong answers |
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| [NEXT-STEPS.md](./NEXT-STEPS.md) | Handoff: what is unverified, what to do next, and the set for a clean PR |
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## Headline result
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Server RAM, merge-base `06724cfeb` vs this branch, two alternated runs per side, reported as cgroup
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**anonymous** memory because that is what counts against a container limit and cannot be reclaimed:
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| stage | before | after | change |
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| --- | --- | --- | --- |
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| **peak** | 376.6 MiB | **279.3 MiB** | **−26%** |
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| boot idle | 130.5 MiB | **62.4 MiB** | **−52%** |
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| after sign-in | 247.4 MiB | **142.9 MiB** | **−42%** |
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| dashboard loaded | 293.4 MiB | **170.4 MiB** | **−42%** |
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| 4 tabs, 2 boards | 366.5 MiB | **258.2 MiB** | **−30%** |
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| after 2 min idle soak | 323.7 MiB | **200.8 MiB** | **−38%** |
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No before/after range overlaps at any stage. The cost is **+18% CPU** (solid, non-overlapping).
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## The changes that did it, by ratio
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| change | size | effect |
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| --- | --- | --- |
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| `--max-semi-space-size=4` | **1 line** | −19% idle, −21% peak |
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| `preloadEntriesOnStart: false` | **1 line** | −52% anon at idle, 310 fewer files even at full load |
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| Umami: stop fetching 100k raw events per refresh | 1 file | −26% peak, −93% transient buffers |
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| `serverExternalPackages` (mysql2/pg + 8 more) | 1 block | −21 MiB idle |
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| ssh2's 16 MiB WASM heap (docker-modem patch) | 1 patch | −15 to −18 MiB external |
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| `content-visibility` on media-release cards | 4 lines | −59% image requests, −41% layout objects |
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## What is left, and why it is hard
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One lever has real headroom and it pays twice. Roughly **41 MiB of retained bundle source** and
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**~38 MiB of V8 compiler zone memory** both scale with how much JavaScript the server loads and
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compiles, and the largest single contributor is a **16.10 MiB subtree reached by every API route** —
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the tRPC router importing every integration eagerly. Reducing that reduces both.
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Everything else has been measured and closed: see [REJECTED.md](./REJECTED.md).
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