feat(rolldown_binding): Add configurable max_blocking_threads with environment variable override by Copilot · Pull Request #5559 · rolldown/rolldown

Copilot · 2025-08-02T14:10:43Z

This PR adds support for configuring the tokio runtime's max_blocking_threads setting in the rolldown_binding crate to optimize multi-threaded IO performance.

Problem

The default tokio runtime configuration may not be optimal for all use cases. Having a configurable max_blocking_threads setting allows for performance tuning based on specific deployment requirements and system characteristics.

Solution

Added a module_init function to the rolldown_binding crate that creates a custom tokio runtime with configurable max_blocking_threads:

Default: Uses tokio's standard default value of 512 threads
Environment override: Supports ROLLDOWN_MAX_BLOCKING_THREADS environment variable for manual tuning
Platform agnostic: Same behavior across all platforms for consistent testing

Implementation Details

The implementation uses #[napi_derive::module_init] to initialize the runtime before any bundling operations:

Checks for ROLLDOWN_MAX_BLOCKING_THREADS environment variable
Falls back to the standard tokio default of 512 threads
Creates the custom runtime using napi::bindgen_prelude::create_custom_tokio_runtime
Only applies to non-WASM targets using conditional compilation

Testing

✅ All existing tests pass
✅ CLI functionality verified with bundling operations
✅ Environment variable override works correctly
✅ No clippy warnings or formatting issues

This approach allows for thorough testing and optimization via the ROLLDOWN_MAX_BLOCKING_THREADS environment variable while maintaining a consistent default behavior across all platforms.

Fixes #3754.

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netlify · 2025-08-02T14:11:18Z

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github-actions · 2025-08-02T15:30:29Z

Benchmarks Rust

target: main(4927fda)
pr: copilot/fix-3754(d39744a)

group                                                        pr                                     target
-----                                                        --                                     ------
bundle/bundle@multi-duplicated-top-level-symbol              1.00     78.0±2.07ms        ? ?/sec    1.08     83.9±4.82ms        ? ?/sec
bundle/bundle@multi-duplicated-top-level-symbol-sourcemap    1.00     88.2±2.37ms        ? ?/sec    1.02     90.4±2.80ms        ? ?/sec
bundle/bundle@rome_ts                                        1.00    115.4±3.36ms        ? ?/sec    1.00    115.1±2.16ms        ? ?/sec
bundle/bundle@rome_ts-sourcemap                              1.00    135.9±1.74ms        ? ?/sec    1.00    135.3±2.02ms        ? ?/sec
bundle/bundle@threejs                                        1.01     43.0±2.63ms        ? ?/sec    1.00     42.7±2.55ms        ? ?/sec
bundle/bundle@threejs-sourcemap                              1.02     52.4±0.74ms        ? ?/sec    1.00     51.5±1.21ms        ? ?/sec
bundle/bundle@threejs10x                                     1.00    437.0±4.90ms        ? ?/sec    1.01    439.5±5.30ms        ? ?/sec
bundle/bundle@threejs10x-sourcemap                           1.01    522.1±6.89ms        ? ?/sec    1.00    517.3±7.05ms        ? ?/sec
scan/scan@rome_ts                                            1.01     89.7±1.79ms        ? ?/sec    1.00     88.9±1.67ms        ? ?/sec
scan/scan@threejs                                            1.03     31.5±0.67ms        ? ?/sec    1.00     30.5±0.58ms        ? ?/sec
scan/scan@threejs10x                                         1.01    323.3±2.99ms        ? ?/sec    1.00    320.2±4.21ms        ? ?/sec

…t()) Co-authored-by: Boshen <[email protected]>

Boshen · 2025-08-05T10:37:55Z

@copilot remove the #[cfg(target_os = "macos")] and #[cfg(not(target_os = "macos"))] and always use the default.

@IWANABETHATGUY let's land this without any modifications firsts, test it thoroughly via ROLLDOWN_MAX_BLOCKING_THREADS.

…lt value (512) Co-authored-by: Boshen <[email protected]>

Copilot · 2025-08-05T10:46:44Z

@copilot remove the #[cfg(target_os = "macos")] and #[cfg(not(target_os = "macos"))] and always use the default.

@IWANABETHATGUY let's land this without any modifications firsts, test it thorou...

Removed the #[cfg(target_os = "macos")] and #[cfg(not(target_os = "macos"))] conditionals as requested. Now always uses the default value of 512 threads, which allows for thorough testing via the ROLLDOWN_MAX_BLOCKING_THREADS environment variable. Also removed the num_cpus dependency since it's no longer needed. Commit: 5d47dc7

@hyf0

## [1.0.0-beta.32] - 2025-08-11 ### 💥 BREAKING CHANGES - advanceChunks: remove interaction between `advanceChunks` and `preserveEntrySignatures` (#5629) by @hyf0 - types: align `TreeshakingOptions` type with Rollup (#5592) by @sapphi-red ### 🚀 Features - rolldown_plugin_manifest: support legacy (#5694) by @shulaoda - rolldown_plugin_vite_css: align load hook logic (#5667) by @shulaoda - rolldown_plugin_transform: throw error for invalid tsconfig (#5657) by @shulaoda - support `context` option (#5631) by @7086cmd - rolldown: oxc v0.81.0 (#5642) by @Boshen - include plugin name in the message of UNHANDLEABLE_ERRORs that happened in plugins (#5636) by @sapphi-red - pass plugin name to log (#5635) by @sapphi-red - rolldown_plugin_import_glob: support glob-safe paths (#5640) by @shulaoda - rolldown_binding: Add configurable max_blocking_threads with environment variable override (#5559) by @Copilot - output better error message for callable plugins (#5632) by @sapphi-red - rolldown_plugin_manifest: support names for asset (#5627) by @shulaoda - rolldown_plugin_manifest: align the logic related to css entries (#5626) by @shulaoda - hmr: handle `import ... from 'external-module'` in rolldown's best (#5599) by @hyf0 - add array support for `treeshake.moduleSideEffects` option (#5593) by @sapphi-red ### 🐛 Bug Fixes - ensure `./` prefix for relative imports starting with `.` (#5687) by @shulaoda - hmr: fix regression test `deconflict_import_bindings` (#5684) by @hyf0 - hmr: only modules in the propagation chain need to re-execute (#5683) by @hyf0 - preserve empty `export {}` to ensure correct ESM detection (#5686) by @shulaoda - vite test failed (#5675) by @IWANABETHATGUY - incorrect module execution order with sideeffectful CJS module (#5661) by @IWANABETHATGUY - rollup-tests: update ignored tests for `option.context` (#5669) by @situ2001 - hmr: ensure correctness of `typeof require === 'function'` (#5651) by @hyf0 - hmr: rewrite `this` to `exports` for cjs modules (#5641) by @hyf0 - don't generate namespace reexport code for reexport external record that has been moved to entry point (#5622) by @IWANABETHATGUY - esm export * from 'externalized-dep' generates unnecessary code (#5612) by @IWANABETHATGUY - hmr: correct runtime behavior for manual reexports (#5614) by @hyf0 - ci: resolve potential sync issue in `this.emitFile` (#5611) by @shulaoda - hmr: support re-assignment on `module.exports` (#5607) by @hyf0 - hmr: rewrite `require(...)` to sensible form (#5604) by @hyf0 - align behavior when returning `undefined` from `treeshake.moduleSideEffects` function (#5595) by @sapphi-red ### 🚜 Refactor - rolldown_binding: improve the use of `FxHashSet` and `FxHashMap` (#5665) by @shulaoda - hmr: move constants to `constants.rs` (#5650) by @hyf0 - hmr: rewrite `exports,module` to `__rolldown_exports__,__rolldown_module__` (#5647) by @hyf0 - hmr: migrate `VisitMut` to `Traverse` (#5646) by @hyf0 - use `bit_index` function to get `RuntimeHelper` bit index (#5634) by @IWANABETHATGUY - improve `JsCallback` and `MaybeAsyncJsCallback` (#5628) by @shulaoda - use bitflags instead of boolean to represent module_namespace included reason (#5621) by @IWANABETHATGUY - rolldown_debug,rolldown_tracing: remove `EnvFilter` (#5231) by @Boshen - align parameter name for `treeshake.moduleSideEffects` (#5594) by @sapphi-red ### 📚 Documentation - contrib-guide: add CPU profile steps (#5677) by @sapphi-red - rollup-tests: update README to correct commands (#5658) by @situ2001 ### ⚡ Performance - reduce memory usage when calc none wrapped modules implicit dependency (#5679) by @IWANABETHATGUY - hmr: do codegen in parallel (#5590) by @hyf0 ### 🧪 Testing - Runtime error when using rolldown to build a page using tinymce (#5678) by @IWANABETHATGUY - rollup: enable testing for `option.context` (#5663) by @situ2001 - hmr: run patch exectution after the normal execution (#5645) by @sapphi-red - hmr: properly execute patch chunks (#5617) by @sapphi-red - rust/hmr: hide unnecessary rolldown runtime, hmr module (#5606) by @hyf0 - rust/hmr: support writting assertion tests (#5598) by @hyf0 - rust: simplify global variable injection logic (#5597) by @hyf0 ### ⚙️ Miscellaneous Tasks - deps: lock file maintenance (#5693) by @renovate[bot] - deps: lock file maintenance (#5692) by @renovate[bot] - deps: lock file maintenance rust crates (#5691) by @renovate[bot] - deps: update github-actions (#5688) by @renovate[bot] - deps: lock file maintenance npm packages (#5690) by @renovate[bot] - deps: update github-actions (major) (#5689) by @renovate[bot] - upgrade NAPI-RS to 3.2 (#5680) by @Brooooooklyn - deps: update dependency tsdown to v0.14.0 (#5681) by @renovate[bot] - clean up basic-vue example (#5676) by @IWANABETHATGUY - deps: update crate-ci/typos action to v1.35.3 (#5674) by @renovate[bot] - remove duplicate hook tracing (#5673) by @IWANABETHATGUY - deps: update dependency tsdown to v0.13.4 (#5668) by @renovate[bot] - deps: update dependency rolldown-plugin-dts to v0.15.6 (#5666) by @renovate[bot] - deps: update crate-ci/typos action to v1.35.2 (#5664) by @renovate[bot] - deps: update dependency rust to v1.89.0 (#5652) by @renovate[bot] - deps: update dependency rolldown-plugin-dts to v0.15.5 (#5649) by @renovate[bot] - deps: update dependency rolldown-plugin-dts to v0.15.4 (#5638) by @renovate[bot] - add `just debug-test` alias to run test without extended test case (#5633) by @IWANABETHATGUY - update lable related to auto labeled documentation ci (#5630) by @IWANABETHATGUY - clippy: allow `case_sensitive_file_extension_comparisons` (#5625) by @shulaoda - fix wasi build failed (#5624) by @sapphi-red - use env variable to control whether run extended tests (#5623) by @IWANABETHATGUY - remove redundant track_caller (#5620) by @IWANABETHATGUY - replace unmaintained goto-bus-stop/setup-zig with mlugg/setup-zig action (#5605) by @Copilot - deps: update crate-ci/typos action to v1.35.1 (#5603) by @renovate[bot] - deps: update crate-ci/typos action to v1.35.0 (#5601) by @renovate[bot] - deps: update dependency tsdown to v0.13.3 (#5602) by @renovate[bot] - deps: update dependency rolldown-plugin-dts to v0.15.3 (#5600) by @renovate[bot] Co-authored-by: shulaoda <[email protected]>

Copilot AI assigned Copilot and Boshen Aug 2, 2025

Copilot started work on behalf of Boshen August 2, 2025 14:10 View session

Copilot AI changed the title ~~[WIP] [Perf]: Optimize multi thread IO in macOS~~ [Perf]: Optimize multi-thread IO in macOS by limiting max_blocking_threads Aug 2, 2025

Copilot AI requested a review from Boshen August 2, 2025 14:27

Copilot finished work on behalf of Boshen August 2, 2025 14:27

Boshen requested review from Brooooooklyn and IWANABETHATGUY August 2, 2025 15:16

Boshen marked this pull request as ready for review August 2, 2025 15:16

Boshen changed the title ~~[Perf]: Optimize multi-thread IO in macOS by limiting max_blocking_threads~~ feat(rolldown_binding): Optimize multi-thread IO in macOS by limiting max_blocking_threads Aug 2, 2025

Implement macOS multi-thread IO optimization using 4.min(num_cpus::ge…

c82c205

…t()) Co-authored-by: Boshen <[email protected]>

IWANABETHATGUY force-pushed the copilot/fix-3754 branch from 3287a7b to c82c205 Compare August 3, 2025 15:27

Copilot started work on behalf of Boshen August 5, 2025 10:38 View session

Remove platform-specific conditional compilation and always use defau…

d39744a

…lt value (512) Co-authored-by: Boshen <[email protected]>

Copilot AI changed the title ~~feat(rolldown_binding): Optimize multi-thread IO in macOS by limiting max_blocking_threads~~ feat(rolldown_binding): Add configurable max_blocking_threads with environment variable override Aug 5, 2025

Copilot finished work on behalf of Boshen August 5, 2025 10:47

IWANABETHATGUY approved these changes Aug 6, 2025

View reviewed changes

IWANABETHATGUY added this pull request to the merge queue Aug 6, 2025

Merged via the queue into main with commit cb41f28 Aug 6, 2025
24 checks passed

IWANABETHATGUY deleted the copilot/fix-3754 branch August 6, 2025 12:52

github-actions bot mentioned this pull request Aug 11, 2025

release: v1.0.0-beta.32 #5699

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feat(rolldown_binding): Add configurable max_blocking_threads with environment variable override#5559

feat(rolldown_binding): Add configurable max_blocking_threads with environment variable override#5559
IWANABETHATGUY merged 2 commits intomainfrom
copilot/fix-3754

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