perf: replace TypedDashMap with TypedMap in CustomField#8708
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graphite-app[bot] merged 1 commit intomainfrom Mar 15, 2026
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perf: replace TypedDashMap with TypedMap in CustomField#8708graphite-app[bot] merged 1 commit intomainfrom
graphite-app[bot] merged 1 commit intomainfrom
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Pull request overview
This PR replaces TypedDashMap (a concurrent DashMap-backed typed map) with TypedMap (a plain HashMap-backed typed map) in the CustomField type. Since CustomField follows a write-once-then-share pattern (populated at creation, wrapped in Arc, then only read), the concurrent write overhead of DashMap (64 shards × 8 KB = 512 KB per instance) is unnecessary.
Changes:
- Replaced
TypedDashMapwithTypedMapinCustomField, addingDerefMutimpl and a manualDebugimpl - Updated all call sites to use
let mutbefore inserting intoCustomField(required sinceTypedMap::insertneeds&mut selfunlikeDashMap) - Removed the
dashmapfeature dependency from thetypedmapcrate inCargo.toml
Reviewed changes
Copilot reviewed 6 out of 7 changed files in this pull request and generated no comments.
Show a summary per file
| File | Description |
|---|---|
crates/rolldown_plugin/src/types/custom_field.rs |
Core change: swap TypedDashMap → TypedMap, add DerefMut, manual Debug |
crates/rolldown_plugin/Cargo.toml |
Remove dashmap feature from typedmap dependency |
crates/rolldown_binding/src/options/plugin/binding_callable_builtin_plugin.rs |
Add mut to CustomField creation |
crates/rolldown_binding/src/options/plugin/types/binding_plugin_context_resolve_options.rs |
Add mut to CustomField creation |
crates/rolldown_plugin_vite_import_glob/src/utils.rs |
Add mut and wrap in Arc after mutation |
crates/rolldown/tests/rolldown/plugin/plugin_context/custom_arg_in_resolve/mod.rs |
Add mut to test's CustomField creation |
Cargo.lock |
Remove dashmap transitive dependency from typedmap |
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Benchmarks Rust |
Merging this PR will not alter performance
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Footnotes
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@copilot add a design note |
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hyf0
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Mar 15, 2026
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Pull request overview
This PR replaces TypedDashMap (backed by DashMap with 64 shards) with TypedMap (backed by a plain HashMap) in the CustomField type used for plugin context resolve options. Since CustomField is always populated before being shared via Arc and then only read, the concurrent-write overhead of DashMap is unnecessary, saving ~24 MB of shard allocation overhead in production.
Changes:
- Swapped the inner type of
CustomFieldfromTypedDashMaptoTypedMap, addingDerefMutand a manualDebugimpl - Updated all call sites to use
let mutbefore inserting intoCustomField, then wrapping inArc - Removed the
dashmapfeature from thetypedmapdependency and added a design note explaining the rationale
Reviewed changes
Copilot reviewed 8 out of 9 changed files in this pull request and generated no comments.
Show a summary per file
| File | Description |
|---|---|
crates/rolldown_plugin/src/types/custom_field.rs |
Core change: replace TypedDashMap with TypedMap, add DerefMut, manual Debug |
crates/rolldown_plugin/Cargo.toml |
Remove dashmap feature from typedmap dependency |
crates/rolldown_binding/src/options/plugin/binding_callable_builtin_plugin.rs |
Add mut to CustomField creation before insert |
crates/rolldown_binding/src/options/plugin/types/binding_plugin_context_resolve_options.rs |
Add mut to CustomField creation before insert |
crates/rolldown_binding/src/options/plugin/js_plugin.rs |
Replace `.map( |
crates/rolldown_plugin_vite_import_glob/src/utils.rs |
Insert into mutable CustomField before wrapping in Arc |
crates/rolldown/tests/rolldown/plugin/plugin_context/custom_arg_in_resolve/mod.rs |
Test updated for mut pattern |
meta/design/plugin-context-resolve.md |
Design rationale document |
Cargo.lock |
Reflects removal of dashmap transitive dependency from typedmap |
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## Summary - Replace `TypedDashMap` (DashMap-backed, 64 shards × 8 KB = 512 KB per instance) with `TypedMap` (plain HashMap-backed) in `CustomField` - `CustomField` is write-once-read-many: populated at creation, wrapped in `Arc`, then only read — concurrent write access is never needed - Removes `dashmap` feature dependency from `typedmap` crate Before (from earlier profiling): - DashMap shard allocations from CustomField: ~24.2 MB in 3,104 blocks - Total allocated: ~311 MB After (with TypedMap): - DashMap shard overhead (remaining, from other DashMaps like resolver/file emitter): 0.17 MB in ~17 blocks - TypedMap/CustomField allocations: 0.15 MB - Total allocated: 301.2 MB The CustomField DashMap shard overhead dropped from ~24 MB to ~0.15 MB — a ~24 MB reduction (~99.4% elimination). The remaining 0.17 MB of DashMap shard allocations come from other legitimate concurrent DashMaps (resolver cache, file emitter, etc.), not from CustomField. The total allocation reduction of ~10 MB (311 → 301 MB) is less than the full 24 MB because this is a single-threaded dhat run (fewer shards per DashMap than the 64-shard production scenario). The savings on a 10+ core production machine would be the full ~24 MB. 🤖 Generated with [Claude Code](https://claude.com/claude-code)
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## [1.0.0-rc.10] - 2026-03-18 ### 🚀 Features - add indentExclusionRanges property to MagicString (#8746) by @IWANABETHATGUY - expose `oxcRuntimePlugin` (#8654) by @sapphi-red - rust: make bundler generic over FileSystem for in-memory benchmarks (#8652) by @Boshen ### 🐛 Bug Fixes - rolldown_plugin_vite_dynamic_import_vars: align dynamic import fast check with Vite (#8760) by @shulaoda - renamer: handle existing bindings in nested scopes when finding unique names (#8741) by @drewolson - pass `yarn_pnp` option where needed (#8736) by @sapphi-red - preserve optional chaining in namespace member expr rewrite (#8712) by @Copilot - correct UTF-16 index handling in native MagicString (#8693) by @IWANABETHATGUY - mark failing doctests as ignore (#8700) by @Boshen - prevent may_partial_namespace from leaking through include_module (#8682) by @IWANABETHATGUY - ci: bump native-build cache key to invalidate stale napi-rs artifacts (#8678) by @Boshen - `comments.annotation: false` breaking tree-shaking (#8657) by @IWANABETHATGUY - validate filenames for NUL bytes from chunkFileNames/entryFileNames (#8644) by @IWANABETHATGUY - dce-only minify should not set NODE_ENV to production (#8651) by @IWANABETHATGUY ### 🚜 Refactor - rust: remove dead `CrossModuleOptimizationConfig::side_effects_free_function_optimization` (#8673) by @Dunqing - rust: simplify `cross_module_optimization` by removing redundant scope tracking (#8672) by @Dunqing - simplify string repeat in guess_indentor (#8753) by @IWANABETHATGUY - consolidate custom magic-string tests into one file (#8696) by @IWANABETHATGUY - extract CJS bailout checks from include_symbol (#8683) by @IWANABETHATGUY - rust: remove `BindingIdentifierExt` to use `BindingIdentifier::symbol_id()` instead (#8667) by @Dunqing - bench: add bench_preset helper and inline presets (#8658) by @Boshen - rust: filter external modules from entries instead of mapping bit positions (#8637) by @Dunqing ### 📚 Documentation - clarify watch mode behavior and its limitations (#8751) by @sapphi-red - add external link icon to GitHub button in Hero section (#8731) by @thisisnkc - guide: clarify that `inject` option is only conceptually similar to esbuild's one (#8743) by @sapphi-red - meta/design: add `devtools.md` (#8663) by @hyf0 - add viteplus alpha announcement banner (#8668) by @shulaoda ### ⚡ Performance - rolldown: some minor perf optimization found by autoresearch (#8730) by @Brooooooklyn - replace Vec allocation with lazy iterator in find_hash_placeholders (#8703) by @Boshen - replace TypedDashMap with TypedMap in CustomField (#8708) by @Boshen - bench: remove scan benchmark binary to halve LTO link time (#8694) by @Boshen ### 🧪 Testing - watch: increase timeout for error output (#8766) by @sapphi-red - vite-tests: remove JS plugin tests (#8767) by @sapphi-red - watch: add CLI exit code test (#8752) by @sapphi-red - normalize paths on Windows even if `resolve.symlinks` is false (#8483) by @sapphi-red ### ⚙️ Miscellaneous Tasks - correct comment in bundle-analyzer-plugin.ts (#8770) by @origami-z - upgrade oxc to 0.120.0 (#8764) by @Boshen - enable all test for `reset` category in MagicString.test.ts (#8749) by @IWANABETHATGUY - deps: update test262 submodule for tests (#8742) by @sapphi-red - deps: update oxc apps (#8734) by @renovate[bot] - deps: update softprops/action-gh-release action to v2.6.1 (#8724) by @renovate[bot] - deps: update npm packages (major) (#8722) by @renovate[bot] - deps: update github-actions (major) (#8721) by @renovate[bot] - deps: update softprops/action-gh-release action to v2.6.0 (#8720) by @renovate[bot] - deps: update npm packages (#8718) by @renovate[bot] - deps: update rust crates (#8717) by @renovate[bot] - deps: update github-actions (#8716) by @renovate[bot] - deps: update dependency oxlint-tsgolint to v0.17.0 (#8713) by @renovate[bot] - deps: bump cargo-shear to v1.11.2 (#8711) by @Boshen - use org level `CODE_OF_CONDUCT.md` (#8706) by @sapphi-red - fix cache key mismatch and remove redundant cache saves (#8695) by @Boshen - deps: update oxc apps (#8692) by @renovate[bot] - deps: update oxc apps (#8649) by @renovate[bot] - should do matrix out side of reusable workflows 2 (#8691) by @hyf0 - should do matrix out side of reusable workflows (#8690) by @hyf0 - deps: update dependency rolldown-plugin-dts to v0.22.5 (#8689) by @renovate[bot] - upgrade oxc to 0.119.0 and oxc_resolver to 11.19.1 (#8686) by @Boshen - correct if condition of `type-check` job (#8677) by @hyf0 - Gate CI type-check job on node changes (#8669) by @Copilot - benchmark: improve codspeed build (#8665) by @Boshen - deps: update oxc to v0.118.0 (#8650) by @renovate[bot] - deps: update crate-ci/typos action to v1.44.0 (#8647) by @renovate[bot] - deps: update oxc resolver to v11.19.1 (#8646) by @renovate[bot] - deps: update dependency rust to v1.94.0 (#8648) by @renovate[bot] - deps: update dependency rolldown-plugin-dts to v0.22.4 (#8645) by @renovate[bot] ###◀️ Revert - Revert "ci: Gate CI type-check job on node changes" (#8674) by @hyf0 - "chore(deps): update dependency rust to v1.94.0 (#8648)" (#8660) by @shulaoda ### ❤️ New Contributors * @origami-z made their first contribution in [#8770](#8770) * @drewolson made their first contribution in [#8741](#8741) * @thisisnkc made their first contribution in [#8731](#8731) Co-authored-by: shulaoda <165626830+shulaoda@users.noreply.github.com>
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Summary
Replace
TypedDashMap(DashMap-backed, 64 shards × 8 KB = 512 KB per instance) withTypedMap(plain HashMap-backed) inCustomFieldCustomFieldis write-once-read-many: populated at creation, wrapped inArc, then only read — concurrent write access is never neededRemoves
dashmapfeature dependency fromtypedmapcrateBefore (from earlier profiling):
After (with TypedMap):
The CustomField DashMap shard overhead dropped from ~24 MB to ~0.15 MB — a ~24 MB reduction (~99.4% elimination). The remaining 0.17 MB of
DashMap shard allocations come from other legitimate concurrent DashMaps (resolver cache, file emitter, etc.), not from CustomField.
The total allocation reduction of ~10 MB (311 → 301 MB) is less than the full 24 MB because this is a single-threaded dhat run (fewer shards
per DashMap than the 64-shard production scenario). The savings on a 10+ core production machine would be the full ~24 MB.
🤖 Generated with Claude Code