dockerode/lib/docker.js required './session' at module scope, which pulls in
@grpc/grpc-js and @grpc/proto-loader - 112 files. Its single call site is inside
Docker.prototype.buildImage, the BuildKit path. Homarr lists, starts and stops
containers and never builds images, so every install with a Docker widget paid for
a gRPC stack it cannot reach.
Measured with a forced GC, in context rather than in a bare process: requiring
dockerode goes from +26.6 MiB RSS / 5.2 MiB heap to +20.6 MiB / 2.7 MiB, with grpc
and protobufjs files going 63 and 49 to zero.
The bare-process figure was +24.1 MiB, and quoting that would have overstated the
win by 4x - most of it overlaps with what dockerode loads anyway. The patch comment
records the in-context number.
Profiling at the memory high-water mark - not at idle, which is what every earlier
round measured - found the largest single retainer in every snapshot was one V8
Context holding a 16.00 MiB ArrayBuffer. Expanding it through the dominator tree
named it: ssh2's crypto module, whose POLY1305_WASM_MODULE instantiates a
WebAssembly memory for ChaCha20-Poly1305 as soon as it is required.
Homarr has no SSH feature and does not depend on ssh2. The chain is
dockerode -> docker-modem -> ssh2, and docker-modem/lib/modem.js requires './ssh'
at module scope while using it in exactly one place, already guarded by
`protocol === 'ssh'`. A pnpm patch moves the require inside that branch. SSH-based
Docker hosts still work - require() is cached, so they pay it once - and every
socket-based install, which is everyone else, never loads it.
Measured over four alternated runs on a restored real backup, external memory:
before after
board loaded 25.4, 25.1 8.3, 11.2
nav-01 28.5, 25.4 10.1, 8.6
multi-tab 31.1, 35.8 13.0, 10.0
post-soak 21.4, 21.5 5.5, 7.2
Consistently -15 to -18 MiB, ranges non-overlapping, and 30 fewer files loaded
(1470 -> 1440).
Peak RSS does NOT improve, and that is worth stating plainly: V8 sizes its heap
against available headroom, so freeing native memory lets it grow further before
collecting. What changes is the composition - a fixed 16 MiB of unusable WASM
buffer becomes headroom the app can actually use, which matters under a container
memory limit but does not move the peak number.
Also adds the instruments this needed. A heap snapshot can never explain a peak,
because V8 runs a full GC before serialising one and reports only survivors:
- memory-probe.cjs gains in-process allocation sampling, on-demand snapshots via
v8.writeHeapSnapshot, an smaps endpoint, and require-graph recording.
- analyze-allocations.mjs diffs two stages to isolate what one stage allocated.
- analyze-smaps-stages.mjs splits each stage's RSS into JS heap, JIT, native and
file-backed pages.
- analyze-heap-dominators.mjs can now expand the largest retainer, which is what
identified ssh2. A plain graph walk escapes through __proto__ and is useless.
One trap recorded in the findings: taking the peak snapshot over CDP delivers it as
JS string chunks and added ~134 MiB of ArrayBuffers to the process being measured,
producing a fake 693 MiB reading. v8.writeHeapSnapshot streams from C++ instead, and
the probe now reports its own observerCostMiB so the cost of looking is visible.
Ablation (PHASE2-FINDINGS.md) attributed the memory win to the
serverExternalPackages line and the integrations barrel diet. These three
measured at exactly zero and were most of the file churn, so they go:
next-cache-handler: orphaned. cacheHandlers and cacheComponents are both
already gone from next.config.ts and nothing imported the package — it
was reachable only through a stale dependency entry.
cache-tags / cache-invalidation: there is no "use cache", cacheTag,
cacheLife or unstable_cache anywhere in app source, so revalidateTag was
firing on tags nothing registers, with no handler to receive them, inside
a catch that swallowed the resulting out-of-scope error. Removing the
calls also removed the SELECTs that existed only to supply a board name
or member list to them, so board.ts, group.ts, user.ts, serverSettings.ts,
section-router.ts and change-search-preferences.ts return to the
merge-base exactly. The live in-process integration data cache is
untouched.
Redis 6 -> 2 client consolidation: no measurable effect at idle (139.3 vs
139.2 MiB) or under load. Reverted, but the pubSub:last:* TTL is kept —
that one is an unbounded-growth fix, not a consolidation.
23 files, -883 lines. Diff vs merge-base: 100 files/3336 insertions ->
82 files/2484. pnpm test 144/144 files, 1795 tests, 0 failures;
typecheck and lint clean; app and Docker image build.
Next.js 16.2.9 does not fully support TypeScript 7 (tsgo) as the
primary typescript package. The Go-native compiler has no in-process
JavaScript API — lib/typescript.js is missing — which causes Next.js's
hasNecessaryDependencies check to fail and the build to SIGABRT with
CI=true. Vercel is working on native tsgo integration expected in Q3
2026 alongside TypeScript 7 stable.
Thomas Camlong
homarr-renovate[bot]