From d0979f368eed1f11d88e763f98c846d9b4636752 Mon Sep 17 00:00:00 2001
From: JJ Kasper <jj@jjsweb.site>
Date: Mon, 28 Oct 2019 15:05:40 -0500
Subject: [PATCH] Disable worker_threads by default

---
 examples/with-firebase-authentication/next.config.js  |  9 ---------
 .../plugins/terser-webpack-plugin/src/TaskRunner.js   |  2 +-
 packages/next/next-server/server/config.ts            |  2 +-
 test/integration/firebase-grpc/test/index.test.js     | 11 +++++------
 4 files changed, 7 insertions(+), 17 deletions(-)
 delete mode 100644 examples/with-firebase-authentication/next.config.js

diff --git a/examples/with-firebase-authentication/next.config.js b/examples/with-firebase-authentication/next.config.js
deleted file mode 100644
index ff566d92fe871..0000000000000
--- a/examples/with-firebase-authentication/next.config.js
+++ /dev/null
@@ -1,9 +0,0 @@
-// Parallel builds are currently broken due to a limitation in grpc (a transitive firebase
-// dependency). Until this is fixed, a workaround is to set the number of available CPUs to 1.
-// https://github.com/zeit/next.js/issues/7894
-// https://github.com/grpc/grpc-node/issues/778
-module.exports = {
-  experimental: {
-    cpus: 1
-  }
-}
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 469de3051b486..b306966292ede 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
@@ -28,8 +28,8 @@ export default class TaskRunner {
 
     if (this.maxConcurrentWorkers > 1) {
       this.workers = new Worker(worker, {
-        numWorkers: this.maxConcurrentWorkers,
         enableWorkerThreads: true,
+        numWorkers: this.maxConcurrentWorkers,
       })
       this.boundWorkers = options => this.workers.default(options)
     } else {
diff --git a/packages/next/next-server/server/config.ts b/packages/next/next-server/server/config.ts
index 7c742c14889c3..97a8745c9ab9f 100644
--- a/packages/next/next-server/server/config.ts
+++ b/packages/next/next-server/server/config.ts
@@ -48,7 +48,7 @@ const defaultConfig: { [key: string]: any } = {
     publicDirectory: false,
     sprFlushToDisk: true,
     deferScripts: false,
-    workerThreads: true,
+    workerThreads: false,
   },
   future: {
     excludeDefaultMomentLocales: false,
diff --git a/test/integration/firebase-grpc/test/index.test.js b/test/integration/firebase-grpc/test/index.test.js
index 270d3d2b93699..b3aa63e39a882 100644
--- a/test/integration/firebase-grpc/test/index.test.js
+++ b/test/integration/firebase-grpc/test/index.test.js
@@ -10,7 +10,10 @@ const nextConfig = path.join(appDir, 'next.config.js')
 
 describe('Builds with firebase dependency only sequentially', () => {
   it('Throws an error when building with firebase dependency with worker_threads', async () => {
-    await fs.remove(nextConfig)
+    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(
@@ -19,12 +22,8 @@ describe('Builds with firebase dependency only sequentially', () => {
   })
 
   it('Throws no error when building with firebase dependency without worker_threads', async () => {
-    await fs.writeFile(
-      nextConfig,
-      `module.exports = { experimental: { workerThreads: false } }`
-    )
-    const results = await nextBuild(appDir, [], { stdout: true, stderr: true })
     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\./