parallel-webpack

2.6.0 verified Sat Apr 25 auth: no javascript

Build multiple webpack configurations in parallel using all CPU cores. Current stable version is 2.6.0 (released 2020), with an alpha 3.0.0 that drops watch mode and switches from worker-farm to jest-worker. Reduces build times dramatically (e.g., from 16 min to 2 min for 32 variants). Key differentiator: built-in createVariants helper for generating configuration combinations without manual config arrays.

Common errors

error Error: Cannot find module 'parallel-webpack' ↓

cause Local install missing or global install not in PATH.

fix

Run npm install parallel-webpack --save-dev and use npx parallel-webpack.

error Error: webpack version mismatch; expected ^1.12.9 || ^2.2.0 || ^3.x || ^4.x but found 5.x ↓

cause Webpack 5 is not in the peer dependency range.

fix

Install webpack 4: npm install webpack@4 --save-dev.

error TypeError: createVariants is not a function ↓

cause Using `require('parallel-webpack')` directly; createVariants is a named export.

fix

Use const { createVariants } = require('parallel-webpack');

Warnings

breaking v3.0.0-alpha.1 drops watch mode support; use v2.6.x if you need --watch. ↓

fix Stay on v2.6.0 or implement custom watch logic.

breaking v3.0.0-alpha.1 changes worker-farm to jest-worker; may affect error handling and output. ↓

fix Test with your config; upgrade only after validating behavior.

deprecated Webpack 4 support is stable but Webpack 5 is not officially supported. ↓

fix Use webpack 4 or test with webpack 5 at your own risk.

gotcha Config function that returns a promise of config array is only supported since v2.5.0. ↓

fix Update to v2.5.0+ or export a static array.

gotcha Worker processes may not exit cleanly on error; unhandled rejections cause build failure since v2.6.0. ↓

fix Update to v2.6.0+; older versions may hang.

Install

npm install parallel-webpack

yarn add parallel-webpack

pnpm add parallel-webpack

Imports

createVariants
wrong
```
const createVariants = require('parallel-webpack').createVariants;
```
correct
```
import { createVariants } from 'parallel-webpack'
```
Package supports both ESM and CJS; CJS require works but named import is preferred for modern code.
default (run CLI)
wrong
```
require('parallel-webpack')()
```
correct
```
parallel-webpack (CLI command)
```
Primary usage is via CLI; programmatic API is minimal.
run (programmatic)
```
const { run } = require('parallel-webpack'); run(configs, options);
```
Undocumented but available in source; use only if you need programmatic control.

Quickstart

Demonstrates basic usage: exporting an array of configs and running via CLI to build in parallel.

// webpack.config.js
var path = require('path');
module.exports = [{
  entry: './pageA.js',
  output: {
    path: path.resolve(__dirname, './dist'),
    filename: 'pageA.bundle.js'
  }
}, {
  entry: './pageB.js',
  output: {
    path: path.resolve(__dirname, './dist'),
    filename: 'pageB.bundle.js'
  }
}];

// CLI: npx parallel-webpack --config webpack.config.js