System:
  OS: macOS 15.6
  CPU: (10) arm64 Apple M1 Max
  Memory: 1.57 GB / 64.00 GB
  Shell: 5.9 - /bin/zsh
Binaries:
  Node: 20.15.1 - ~/.volta/tools/image/node/20.15.1/bin/node
  Yarn: 4.2.2 - ~/.volta/tools/image/yarn/4.2.2/bin/yarn
  npm: 10.7.0 - ~/.volta/tools/image/node/20.15.1/bin/npm
  pnpm: 10.14.0 - ~/.volta/bin/pnpm
npmPackages:
  unplugin: 2.3.7 => 2.3.7 

# create a new project
mkdir unplugin-repro-multiprocess-rspack-virtual
cd unplugin-repro-multiprocess-rspack-virtual
# init and add packages
pnpm init
pnpm add -D @rspack/core unplugin
# create src files
mkdir src
cat << EOF > src/one.js
import "virtual:console.log('one')"
EOF
cat << EOF > src/two.js
import "virtual:console.log('two')"
EOF
# create a dummy plugin that resolves and load virtual files
cat << EOF > virtual-code-plugin.js
const { createUnplugin } = require("unplugin");

module.exports = createUnplugin((delay = 0) => ({
  name: "virtual-code-plugin",
  async resolveId(id) {
    if (id.startsWith("virtual:")) {
        await new Promise(resolve => setTimeout(resolve, delay));
        return id
    }
  },
  load: {
    filter: {
        id: /^virtual:/
    },
    handler(id) {
        return id.slice(8);
    }
  }
}));
EOF
# create a build script that forks the process and runs the compiler in parallel twice
cat << EOF > build.js
const child_process = require('node:child_process');
const process = require('node:process');
const rspack = require('@rspack/core');
const VirtualCodePlugin = require('./virtual-code-plugin');

let isChild = process.argv[2] === 'child';
if(!isChild) { child_process.fork(process.argv[1], ['child']) }

const compiler = rspack({
    entry: isChild ? { one: './src/one.js' } : { two: './src/two.js' },
    target: 'web',
    plugins: [VirtualCodePlugin.rspack(isChild ? 0 : 500)],
    devtool: false
});

compiler.run(function(err, stats) {
    if (err) {
        console.error(err);
    } else {
        console.log(stats.toString());
    }
    compiler.close((error) => {
        if (error) {
            console.error(error);
        }
    });
});
EOF
# the build will crash, because the child process will delete the virtual folder while the parent is still running
node build.js

node build.js
asset one.js 481 bytes [emitted] (name: one)
runtime modules 730 bytes 5 modules
cacheable modules 54 bytes
  ./src/one.js 36 bytes [built] [code generated]
  ./node_modules/.virtual/virtual%3Aconsole.log('one') 18 bytes [built] [code generated]
Rspack 1.4.11 compiled successfully in 324 ms
assets by status 314 bytes [cached] 1 asset
runtime modules 93 bytes 2 modules
./src/two.js 36 bytes [built] [code generated] [1 error]

ERROR in ./src/two.js 1:0-35
  × Error: ENOENT: no such file or directory, open '/Users/julien.elbaz/dev/experiments/unplugin-repro-multiprocess-rspack-virtual/node_modules/.virtual/virtual%3Aconsole.log('two')'
  │     at async open (node:internal/fs/promises:633:25)
  │     at async Object.writeFile (node:internal/fs/promises:1207:14)
  │     at async FakeVirtualModulesPlugin.writeModule (/Users/julien.elbaz/dev/experiments/unplugin-repro-multiprocess-rspack-virtual/node_modules/.pnpm/unplugin@2.3.7/node_modules/unplugin/dist/utils-D30tqOw3.cjs:34:3)
  │     at async /Users/julien.elbaz/dev/experiments/unplugin-repro-multiprocess-rspack-virtual/node_modules/.pnpm/unplugin@2.3.7/node_modules/unplugin/dist/index.cjs:746:10
  │

Rspack 1.4.11 compiled with 1 error in 670 ms