feat(babel): add parallel processing via worker threads #1956
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- drops support for rollup 1.x, which allows simplifying the implementation - implements 'plugin hook filters' for improved performance under rolldown - passes a new `code` argument to custom filter functions, so that consumers can add more advanced filtering logic - allows custom filter functions to be async
Add a `parallel` option that processes files concurrently using Node.js worker threads. This reduces build times for large projects where Babel transformation is a bottleneck. This is similar to the existing parallel behavior of `@rollup/plugin-terser`. This required some fairly significant refactoring, because we can only pass serializable objects between the main thread and the worker threads. It also required changes to the plugin's own build config, so that we can generate a dedicated worker entrypoint. Validations are added to ensure that unserializable config (e.g. inline babel plugins) cannot be used alongside the new parallel mode. For people using dedicated babel config files, this isn't a problem, because they are loaded directly by babel in the worker thread itself. The worker threads do have a setup cost, so this only makes sense for large projects. In Discourse, enabling this parallel mode cuts our overall vite (rolldown) build time by about 45% (from ~11s to ~6s) on my machine.
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Rollup Plugin Name:
@rollup/plugin-babelThis PR contains:
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If yes, then include "BREAKING CHANGES:" in the first commit message body, followed by a description of what is breaking.
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Description
feat(babel): add parallel processing via worker threads
Add a
paralleloption that processes files concurrently using Node.js worker threads. This reduces build times for large projects where Babel transformation is a bottleneck. This is similar to the existing parallel behavior of@rollup/plugin-terser.This required some fairly significant refactoring, because we can only pass serializable objects between the main thread and the worker threads. It also required changes to the plugin's own build config, so that we can generate a dedicated worker entrypoint.
Validations are added to ensure that unserializable config (e.g. inline babel plugins) cannot be used alongside the new parallel mode. For people using dedicated babel config files, this isn't a problem, because they are loaded directly by babel in the worker thread itself.
The worker threads do have a setup cost, so this only makes sense for large projects. In Discourse, enabling this parallel mode cuts our overall vite (rolldown) build time by about 45% (from ~11s to ~6s) on my machine.
This PR is based on #1954, which should ideally be merged first. Happy to rebase this one on
mainif the other PR isn't mergable.For testing, I've pushed a built version of this branch to https://github.com/davidtaylorhq/plugins/tree/babel-parallel-built. In pnpm, it can be installed like: