perf(sourcemap): owned merge in SourceJoiner::join (4005->5 allocs/chunk)#10250
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hyfdev
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No issues from side, I think it's good to merge, but there're some nit comments from others. |
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…unk) (#10250) `SourceJoiner::join` borrowed every input map's strings into a `ConcatSourceMapBuilder`, then called `into_owned` on the merged result to detach it — deep-copying every name/source/sourcesContent string of every module, one heap allocation each, on the per-chunk codegen path. This moves each source's owned `SourceMap` into the builder via `ConcatSourceMapBuilder::add_sourcemap_owned`; the merged map is already `'static`, so the trailing `into_owned` is gone. Sources that can only lend a borrowed map (e.g. one shared through an `Arc`) fall back to `add_sourcemap` + copy-on-detach, so output is unchanged. Measured via `tasks/track_memory_allocations` (2000-module chunk): ``` sourcemap/join_with_sourcemap 4005 -> 5 allocs ``` A second commit refines the join: it takes `&mut self` — the merge only needs `iter_mut()` + `take_sourcemap()`, so it never needed to consume `self` — and the benches move to `iter_batched_ref` so the micro-bench stops timing the per-iteration joiner teardown (that teardown, not the concat, was the spurious `join_no_sourcemap` CodSpeed delta). It also skips the newline scan of the *final* joined source, whose line count only advances the offset for a following source. This is the focused, measured core extracted from #9881 (original work by @hyf0). It touches only `rolldown_sourcemap` plus the benches/allocation snapshot; the `ecma_generator`/format pipeline is left untouched, so real-build sourcemap output is identical to `main`. Wiring the chunk renderer to hand `join` its owned per-module maps — instead of the `Arc`-shared borrow it copies today — is a follow-up.
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## [1.2.0] - 2026-07-15 ### 🚀 Features - dev: skip shipping factories for newly imported top-level modules (#10223) by @h-a-n-a - dev: per-client ship map for HMR patch sizing (#10208) by @h-a-n-a - dev: client-side HMR (#10164) by @h-a-n-a - dev: send a full-reload update to clients when a tsconfig changes (#10262) by @shulaoda - treat `import.meta['url']` and `import.meta['ROLLUP_FILE_URL_*']` as side-effect free (#10267) by @sapphi-red - rewrite `import.meta['url']` (#10251) by @sapphi-red - add `FILE_NOT_FOUND` error (#10220) by @sapphi-red - treat `import.meta.ROLLUP_FILE_URL_*` as side-effect free (#10217) by @sapphi-red ### 🐛 Bug Fixes - sourcemap: preserve unmapped boundaries during composition (#10254) by @hyfdev - `[format]` in `*FileNames` option for ESM format should be `es` instead of `esm` (#10214) by @sapphi-red - sourcemap: preserve coarse mappings during composition (#10249) by @hyfdev - rolldown_plugin_vite_import_glob: support tsconfig paths with `import.meta.glob` (#10167) by @sapphi-red - dev: clear tsconfig caches for bare full builds (#10276) by @shulaoda - dev: force a full rebuild when a tsconfig changes (#10261) by @shulaoda - treat rooted drive-less module ids as absolute in preserveModules naming (#10235) by @IWANABETHATGUY - watch: rebuild when tsconfig files change (#10258) by @shulaoda - watch: drop tsconfig-merged transform options on each rebuild (#10257) by @shulaoda - incorrect `EMPTY_IMPORT_META` warning for `import.meta.ROLLUP_FILE_URL_*` for CJS output (#10221) by @sapphi-red - deconflict: rename CJS locals shadowing wrapped-ESM namespace objects (#9970) by @IWANABETHATGUY - rolldown: drop the unused runtime module after entry-level external flattening (#10237) by @IWANABETHATGUY - rolldown: re-propagate has_dynamic_exports to transitive star importers (#10239) by @IWANABETHATGUY - tree-shaking: tree-shake destructured dynamic import namespace bindings (#10213) by @logaretm - s390x: use json-escape-simd 3.1.1 for big-endian JSON escaping fix (#10211) by @satyamg1620 ### 🚜 Refactor - dev: move full-reload to client side (#10207) by @h-a-n-a - readability follow-ups to the ReplaceWith migration (#10286) by @IWANABETHATGUY - replace take_in-then-write-back with ReplaceWith and by-value moves (#10285) by @Boshen - share the main resolver's cache with the transformer's tsconfig lookups (#10205) by @shulaoda - rolldown: extract the ns star-external __reExport emission rule into LinkingMetadata (#10238) by @IWANABETHATGUY - rolldown: unify link/generate diagnostics into a Diagnostics accumulator (#10234) by @IWANABETHATGUY - sourcemap_filenames: drop dead sourcemap-filename plumbing (#10189) by @IWANABETHATGUY - extract external import symbol merging into a method (#10224) by @IWANABETHATGUY - rolldown: skip CJS namespace merging under strict execution order (#10203) by @hyfdev - resolve the manual tsconfig per file instead of once at startup (#10200) by @shulaoda - rolldown: route interop ESM init emission through a shared init-target view (#10202) by @hyfdev - rolldown: collapse vestigial wrap-kind state and share chunk sort helper (#10201) by @hyfdev ### 📚 Documentation - show plugin kinds in JSDoc and each hook's description (#10218) by @sapphi-red - add an explanation about removing imports from external modules without any messages (#10215) by @sapphi-red ### ⚡ Performance - sourcemap: owned merge in SourceJoiner::join (4005->5 allocs/chunk) (#10250) by @Boshen - avoid redundant sourcemap string copies in collapse and minify paths (#10093) by @Boshen ### 🧪 Testing - code-splitting: establish strict-order review baselines (#10287) by @hyfdev - dev: add hot API test cases (#10181) by @h-a-n-a - code-splitting: normalize strict execution order variants (#10277) by @hyfdev - code-splitting: harden strict execution order coverage (#10252) by @hyfdev - code-splitting: add strict execution order regressions (#10253) by @hyfdev ### ⚙️ Miscellaneous Tasks - deps: update github actions (#10241) by @renovate[bot] - deps: update oxc to 0.140.0 (#10274) by @shulaoda - update Yunfei's GitHub username (#10275) by @hyfdev - deps: update napi (#10260) by @renovate[bot] - deps: update test262 submodule for tests (#10266) by @rolldown-guard[bot] - deps: update dependency vite-plus to v0.2.4 (#10256) by @renovate[bot] - deps: update napi (#10240) by @renovate[bot] - deps: update oxc resolver to v11.24.2 (#10245) by @renovate[bot] - deps: update rust crates (#10244) by @renovate[bot] - disable Renovate updates for idna_adapter (#10248) by @shulaoda - deps: update oxc resolver to v11.24.1 (#10232) by @renovate[bot] - deps: update rust crate oxc_sourcemap to v8.1.1 (#10233) by @renovate[bot] - deps: update dependency rolldown-plugin-dts to ^0.27.0 (#10206) by @renovate[bot] - deps: upgrade sugar_path to v3 (#10230) by @hyfdev - add `dist-*` to `.gitignore` in sourcemap-filenames/hash-final-content fixture (#10216) by @sapphi-red - deps: update dependency rust to v1.97.0 (#10209) by @renovate[bot] ### ❤️ New Contributors * @satyamg1620 made their first contribution in [#10211](#10211) Co-authored-by: shulaoda <[email protected]>
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SourceJoiner::joinborrowed every input map's strings into aConcatSourceMapBuilder, then calledinto_ownedon the merged result to detach it — deep-copying every name/source/sourcesContent string of every module, one heap allocation each, on the per-chunk codegen path.This moves each source's owned
SourceMapinto the builder viaConcatSourceMapBuilder::add_sourcemap_owned; the merged map is already'static, so the trailinginto_ownedis gone. Sources that can only lend a borrowed map (e.g. one shared through anArc) fall back toadd_sourcemap+ copy-on-detach, so output is unchanged.Measured via
tasks/track_memory_allocations(2000-module chunk):A second commit refines the join: it takes
&mut self— the merge only needsiter_mut()+take_sourcemap(), so it never needed to consumeself— and the benches move toiter_batched_refso the micro-bench stops timing the per-iteration joiner teardown (that teardown, not the concat, was the spuriousjoin_no_sourcemapCodSpeed delta). It also skips the newline scan of the final joined source, whose line count only advances the offset for a following source.This is the focused, measured core extracted from #9881 (original work by @hyf0). It touches only
rolldown_sourcemapplus the benches/allocation snapshot; theecma_generator/format pipeline is left untouched, so real-build sourcemap output is identical tomain. Wiring the chunk renderer to handjoinits owned per-module maps — instead of theArc-shared borrow it copies today — is a follow-up.