From 14ed867537cf200b34b3e6d6b7c810c3fb3983db Mon Sep 17 00:00:00 2001
From: Christoph Tavan <dev@tavan.de>
Date: Tue, 29 Oct 2019 01:01:25 +0100
Subject: [PATCH] Disable worker_threads by default for firebase compatibility
 (#9199)

* Pass config.experimental.cpus to export during build

Currently, there is no way of specifying the number of worker threads of
`next export` when run as part of `next build`.

I suggest a sane default should be to just use the same amount of
workers that were used during the build process which currently seems to
be configured through `config.experimental.cpus`.

This setting is already respected in the two other places where
jest-workers are in use: The TerserPlugin and the staticCheckWorkers in
`next build`.

* Only enable worker threads if there is more than 1 worker

Multiple worker threads can cause problems when certain dependencies are
being used, see e.g. https://github.com/zeit/next.js/issues/7894

This patch allows disabling of worker threads by setting
`config.experimental.cpus = 1`.

The benefit of spawning 1 worker thread, if there is any at all, should
very limited anyways, so the workload can just as well be processed in
the main thread.

* Disable parallel build for firebase authentication example

* Add integration test to cover #7894

* Rename test suite and add worker_threads config

* Disable worker_threads by default

* Update index.test.js

* Use workerThreads config for TerserPlugin

* Update to use workerThreads config in
TerserPlugin for consistency

* Disable node 12 specific test
---
 packages/next/build/index.ts                  |  3 +-
 packages/next/build/webpack-config.ts         |  5 +--
 .../terser-webpack-plugin/src/TaskRunner.js   |  5 +--
 .../terser-webpack-plugin/src/index.js        |  3 ++
 packages/next/export/index.ts                 |  2 +-
 packages/next/next-server/server/config.ts    |  1 +
 .../integration/firebase-grpc/pages/page-1.js |  2 ++
 .../integration/firebase-grpc/pages/page-2.js |  2 ++
 .../firebase-grpc/test/index.test.js          | 33 +++++++++++++++++++
 9 files changed, 50 insertions(+), 6 deletions(-)
 create mode 100644 test/integration/firebase-grpc/pages/page-1.js
 create mode 100644 test/integration/firebase-grpc/pages/page-2.js
 create mode 100644 test/integration/firebase-grpc/test/index.test.js

diff --git a/packages/next/build/index.ts b/packages/next/build/index.ts
index 693fc4803d2da..1d6eefdc45f3f 100644
--- a/packages/next/build/index.ts
+++ b/packages/next/build/index.ts
@@ -337,7 +337,7 @@ export default async function build(dir: string, conf = null): Promise<void> {
 
   const staticCheckWorkers = new Worker(staticCheckWorker, {
     numWorkers: config.experimental.cpus,
-    enableWorkerThreads: true,
+    enableWorkerThreads: config.experimental.workerThreads,
   })
 
   const analysisBegin = process.hrtime()
@@ -471,6 +471,7 @@ export default async function build(dir: string, conf = null): Promise<void> {
       sprPages,
       silent: true,
       buildExport: true,
+      threads: config.experimental.cpus,
       pages: combinedPages,
       outdir: path.join(distDir, 'export'),
     }
diff --git a/packages/next/build/webpack-config.ts b/packages/next/build/webpack-config.ts
index ec50bea7f612c..74b044cdaed42 100644
--- a/packages/next/build/webpack-config.ts
+++ b/packages/next/build/webpack-config.ts
@@ -171,11 +171,12 @@ export default async function getBaseWebpackConfig(
   const webpackMode = dev ? 'development' : 'production'
 
   const terserPluginConfig = {
-    parallel: true,
-    sourceMap: false,
     cache: true,
     cpus: config.experimental.cpus,
     distDir: distDir,
+    parallel: true,
+    sourceMap: false,
+    workerThreads: config.experimental.workerThreads,
   }
   const terserOptions = {
     parse: {
diff --git a/packages/next/build/webpack/plugins/terser-webpack-plugin/src/TaskRunner.js b/packages/next/build/webpack/plugins/terser-webpack-plugin/src/TaskRunner.js
index b306966292ede..d8c0b48df39fd 100644
--- a/packages/next/build/webpack/plugins/terser-webpack-plugin/src/TaskRunner.js
+++ b/packages/next/build/webpack/plugins/terser-webpack-plugin/src/TaskRunner.js
@@ -10,13 +10,14 @@ const writeFileP = promisify(writeFile)
 const readFileP = promisify(readFile)
 
 export default class TaskRunner {
-  constructor({ distDir, cpus, cache }) {
+  constructor({ distDir, cpus, cache, workerThreads }) {
     if (cache) {
       mkdirp.sync((this.cacheDir = join(distDir, 'cache', 'next-minifier')))
     }
     // In some cases cpus() returns undefined
     // https://github.com/nodejs/node/issues/19022
     this.maxConcurrentWorkers = cpus
+    this.useWorkerThreads = workerThreads
   }
 
   run(tasks, callback) {
@@ -28,7 +29,7 @@ export default class TaskRunner {
 
     if (this.maxConcurrentWorkers > 1) {
       this.workers = new Worker(worker, {
-        enableWorkerThreads: true,
+        enableWorkerThreads: this.useWorkerThreads,
         numWorkers: this.maxConcurrentWorkers,
       })
       this.boundWorkers = options => this.workers.default(options)
diff --git a/packages/next/build/webpack/plugins/terser-webpack-plugin/src/index.js b/packages/next/build/webpack/plugins/terser-webpack-plugin/src/index.js
index 1acafe76f9891..4302cb344e4d1 100644
--- a/packages/next/build/webpack/plugins/terser-webpack-plugin/src/index.js
+++ b/packages/next/build/webpack/plugins/terser-webpack-plugin/src/index.js
@@ -21,10 +21,12 @@ export class TerserPlugin {
       cache = false,
       cpus,
       distDir,
+      workerThreads,
     } = options
 
     this.cpus = cpus
     this.distDir = distDir
+    this.workerThreads = workerThreads
     this.options = {
       warningsFilter,
       sourceMap,
@@ -134,6 +136,7 @@ export class TerserPlugin {
         distDir: this.distDir,
         cpus: this.cpus,
         cache: this.options.cache,
+        workerThreads: this.workerThreads,
       })
 
       const processedAssets = new WeakSet()
diff --git a/packages/next/export/index.ts b/packages/next/export/index.ts
index dba1116a3f3d1..2a0ae8b13958c 100644
--- a/packages/next/export/index.ts
+++ b/packages/next/export/index.ts
@@ -267,7 +267,7 @@ export default async function(
     {
       maxRetries: 0,
       numWorkers: threads,
-      enableWorkerThreads: true,
+      enableWorkerThreads: nextConfig.experimental.workerThreads,
       exposedMethods: ['default'],
     }
   ) as any
diff --git a/packages/next/next-server/server/config.ts b/packages/next/next-server/server/config.ts
index 3fe9b13f1a7b3..97a8745c9ab9f 100644
--- a/packages/next/next-server/server/config.ts
+++ b/packages/next/next-server/server/config.ts
@@ -48,6 +48,7 @@ const defaultConfig: { [key: string]: any } = {
     publicDirectory: false,
     sprFlushToDisk: true,
     deferScripts: false,
+    workerThreads: false,
   },
   future: {
     excludeDefaultMomentLocales: false,
diff --git a/test/integration/firebase-grpc/pages/page-1.js b/test/integration/firebase-grpc/pages/page-1.js
new file mode 100644
index 0000000000000..dd9c28611eea2
--- /dev/null
+++ b/test/integration/firebase-grpc/pages/page-1.js
@@ -0,0 +1,2 @@
+import 'firebase/firestore'
+export default () => <div>Firebase</div>
diff --git a/test/integration/firebase-grpc/pages/page-2.js b/test/integration/firebase-grpc/pages/page-2.js
new file mode 100644
index 0000000000000..dd9c28611eea2
--- /dev/null
+++ b/test/integration/firebase-grpc/pages/page-2.js
@@ -0,0 +1,2 @@
+import 'firebase/firestore'
+export default () => <div>Firebase</div>
diff --git a/test/integration/firebase-grpc/test/index.test.js b/test/integration/firebase-grpc/test/index.test.js
new file mode 100644
index 0000000000000..dc24e5fba36de
--- /dev/null
+++ b/test/integration/firebase-grpc/test/index.test.js
@@ -0,0 +1,33 @@
+/* eslint-env jest */
+/* global jasmine */
+import path from 'path'
+import fs from 'fs-extra'
+import { nextBuild } from 'next-test-utils'
+
+jasmine.DEFAULT_TIMEOUT_INTERVAL = 1000 * 60 * 1
+const appDir = path.join(__dirname, '..')
+const nextConfig = path.join(appDir, 'next.config.js')
+
+describe('Building Firebase', () => {
+  // TODO: investigate re-enabling this test in node 12 environment
+  xit('Throws an error when building with firebase dependency with worker_threads', async () => {
+    await fs.writeFile(
+      nextConfig,
+      `module.exports = { experimental: { workerThreads: true } }`
+    )
+    const results = await nextBuild(appDir, [], { stdout: true, stderr: true })
+    expect(results.stdout + results.stderr).toMatch(/Build error occurred/)
+    expect(results.stdout + results.stderr).toMatch(
+      /grpc_node\.node\. Module did not self-register\./
+    )
+  })
+
+  it('Throws no error when building with firebase dependency without worker_threads', async () => {
+    await fs.remove(nextConfig)
+    const results = await nextBuild(appDir, [], { stdout: true, stderr: true })
+    expect(results.stdout + results.stderr).not.toMatch(/Build error occurred/)
+    expect(results.stdout + results.stderr).not.toMatch(
+      /grpc_node\.node\. Module did not self-register\./
+    )
+  })
+})