fix(@angular-devkit/build-angular): limit the amount of CPUs used by workers

See: #16860 (comment)

Author: alan-agius4

packages/angular_devkit/build_angular/src/angular-cli-files/models/webpack-configs/common.ts

@@ -12,7 +12,6 @@ import {
 import { tags } from '@angular-devkit/core';
 import * as CopyWebpackPlugin from 'copy-webpack-plugin';
 import { existsSync } from 'fs';
-import { cpus } from 'os';
 import * as path from 'path';
 import { RollupOptions } from 'rollup';
 import { ScriptTarget } from 'typescript';
@@ -28,8 +27,8 @@ import {
   debug,
 } from 'webpack';
 import { RawSource } from 'webpack-sources';
-import { AssetPatternClass, ExtraEntryPoint } from '../../../browser/schema';
-import { BuildBrowserFeatures } from '../../../utils';
+import { AssetPatternClass } from '../../../browser/schema';
+import { BuildBrowserFeatures, maxWorkers } from '../../../utils';
 import { findCachePath } from '../../../utils/cache-path';
 import {
   allowMangle,
@@ -428,16 +427,10 @@ export function getCommonConfig(wco: WebpackConfigOptions): Configuration {
       mangle: allowMangle && buildOptions.platform !== 'server' && !differentialLoadingMode,
     };
 
-    // Use up to 7 CPUs for Terser workers, but no more.
-    // Some environments, like CircleCI, report a large number of CPUs but trying to use them
-    // Will cause `Error: Call retries were exceeded` errors.
-    // https://github.com/webpack-contrib/terser-webpack-plugin/issues/143
-    const maxCpus = Math.min(cpus().length, 7);
-
     extraMinimizers.push(
       new TerserPlugin({
         sourceMap: scriptsSourceMap,
-        parallel: maxCpus,
+        parallel: maxWorkers,
         cache: !cachingDisabled && findCachePath('terser-webpack'),
         extractComments: false,
         chunkFilter: (chunk: compilation.Chunk) =>
@@ -448,7 +441,7 @@ export function getCommonConfig(wco: WebpackConfigOptions): Configuration {
       // They are shared between ES2015 & ES5 outputs so must support ES5.
       new TerserPlugin({
         sourceMap: scriptsSourceMap,
-        parallel: maxCpus,
+        parallel: maxWorkers,
         cache: !cachingDisabled && findCachePath('terser-webpack'),
         extractComments: false,
         chunkFilter: (chunk: compilation.Chunk) =>

packages/angular_devkit/build_angular/src/utils/action-executor.ts

@@ -12,6 +12,7 @@ import * as v8 from 'v8';
 import { BundleActionCache } from './action-cache';
 import { I18nOptions } from './i18n-options';
 import { InlineOptions, ProcessBundleOptions, ProcessBundleResult } from './process-bundle';
+import { maxWorkers } from './workers';
 
 const hasThreadSupport = (() => {
   try {
@@ -62,6 +63,7 @@ export class BundleActionExecutor {
     return (this.largeWorker = new JestWorker(workerFile, {
       exposedMethods: ['process', 'inlineLocales'],
       setupArgs: [[...serialize(this.workerOptions)]],
+      numWorkers: maxWorkers,
     }));
   }
 

packages/angular_devkit/build_angular/src/utils/index.ts

@@ -16,3 +16,4 @@ export * from './normalize-source-maps';
 export * from './normalize-optimization';
 export * from './normalize-builder-schema';
 export * from './url';
+export * from './workers';

packages/angular_devkit/build_angular/src/utils/workers.ts

@@ -0,0 +1,24 @@
+/**
+ * @license
+ * Copyright Google Inc. All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+
+import { cpus } from 'os';
+/**
+ * Use CPU count -1 with limit to 7 for workers not to clog the system.
+ * Some environments, like CircleCI which use Docker report a number of CPUs by the host and not the count of available.
+ * This cause `Error: Call retries were exceeded` errors when trying to use them.
+ *
+ * See:
+ *
+ * https://github.com/nodejs/node/issues/28762
+ *
+ * https://github.com/webpack-contrib/terser-webpack-plugin/issues/143
+ *
+ * https://github.com/angular/angular-cli/issues/16860#issuecomment-588828079
+ *
+ */
+export const maxWorkers = Math.max(Math.min(cpus().length, 8) - 1, 1);