feat(terser): add maxWorkers option for terserOptions (#13858)

Co-authored-by: bluwy <bjornlu.dev@gmail.com>

docs/config/build-options.md

@@ -209,6 +209,8 @@ npm add -D terser
 
 Additional [minify options](https://terser.org/docs/api-reference#minify-options) to pass on to Terser.
 
+In addition, you can also pass a `maxWorkers: number` option to specify the max number of workers to spawn. Defaults to the number of CPUs minus 1.
+
 ## build.write
 
 - **Type:** `boolean`

packages/vite/src/node/build.ts

@@ -18,7 +18,6 @@ import type {
   RollupWatcher,
   WatcherOptions,
 } from 'rollup'
-import type { Terser } from 'dep-types/terser'
 import commonjsPlugin from '@rollup/plugin-commonjs'
 import type { RollupCommonJSOptions } from 'dep-types/commonjs'
 import type { RollupDynamicImportVarsOptions } from 'dep-types/dynamicImportVars'
@@ -27,7 +26,7 @@ import type { InlineConfig, ResolvedConfig } from './config'
 import { isDepsOptimizerEnabled, resolveConfig } from './config'
 import { buildReporterPlugin } from './plugins/reporter'
 import { buildEsbuildPlugin } from './plugins/esbuild'
-import { terserPlugin } from './plugins/terser'
+import { type TerserOptions, terserPlugin } from './plugins/terser'
 import {
   asyncFlatten,
   copyDir,
@@ -143,8 +142,11 @@ export interface BuildOptions {
   /**
    * Options for terser
    * https://terser.org/docs/api-reference#minify-options
+   *
+   * In addition, you can also pass a `maxWorkers: number` option to specify the
+   * max number of workers to spawn. Defaults to the number of CPUs minus 1.
    */
-  terserOptions?: Terser.MinifyOptions
+  terserOptions?: TerserOptions
   /**
    * Will be merged with internal rollup options.
    * https://rollupjs.org/configuration-options/

packages/vite/src/node/index.ts

@@ -82,6 +82,7 @@ export type { ESBuildOptions, ESBuildTransformResult } from './plugins/esbuild'
 export type { Manifest, ManifestChunk } from './plugins/manifest'
 export type { ResolveOptions, InternalResolveOptions } from './plugins/resolve'
 export type { SplitVendorChunkCache } from './plugins/splitVendorChunk'
+export type { TerserOptions } from './plugins/terser'
 
 export type {
   WebSocketServer,

packages/vite/src/node/plugins/terser.ts

@@ -4,6 +4,16 @@ import type { Plugin } from '../plugin'
 import type { ResolvedConfig } from '..'
 import { requireResolveFromRootWithFallback } from '../utils'
 
+export interface TerserOptions extends Terser.MinifyOptions {
+  /**
+   * Vite-specific option to specify the max number of workers to spawn
+   * when minifying files with terser.
+   *
+   * @default number of CPUs minus 1
+   */
+  maxWorkers?: number
+}
+
 let terserPath: string | undefined
 const loadTerserPath = (root: string) => {
   if (terserPath) return terserPath
@@ -24,6 +34,8 @@ const loadTerserPath = (root: string) => {
 }
 
 export function terserPlugin(config: ResolvedConfig): Plugin {
+  const { maxWorkers, ...terserOptions } = config.build.terserOptions
+
   const makeWorker = () =>
     new Worker(
       async (
@@ -36,6 +48,9 @@ export function terserPlugin(config: ResolvedConfig): Plugin {
         const terser = require(terserPath)
         return terser.minify(code, options) as Terser.MinifyOutput
       },
+      {
+        max: maxWorkers,
+      },
     )
 
   let worker: ReturnType<typeof makeWorker>
@@ -67,7 +82,7 @@ export function terserPlugin(config: ResolvedConfig): Plugin {
       const terserPath = loadTerserPath(config.root)
       const res = await worker.run(terserPath, code, {
         safari10: true,
-        ...config.build.terserOptions,
+        ...terserOptions,
         sourceMap: !!outputOptions.sourcemap,
         module: outputOptions.format.startsWith('es'),
         toplevel: outputOptions.format === 'cjs',