fix(@angular-devkit/build-angular): limit CPUs used by terser-webpack-plugin

Should help with #16860 (comment)

Author: filipesilva

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

@@ -12,6 +12,7 @@ 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';
@@ -427,10 +428,16 @@ 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: true,
+        parallel: maxCpus,
         cache: !cachingDisabled && findCachePath('terser-webpack'),
         extractComments: false,
         chunkFilter: (chunk: compilation.Chunk) =>
@@ -441,7 +448,7 @@ export function getCommonConfig(wco: WebpackConfigOptions): Configuration {
       // They are shared between ES2015 & ES5 outputs so must support ES5.
       new TerserPlugin({
         sourceMap: scriptsSourceMap,
-        parallel: true,
+        parallel: maxCpus,
         cache: !cachingDisabled && findCachePath('terser-webpack'),
         extractComments: false,
         chunkFilter: (chunk: compilation.Chunk) =>