fix: memory leak when frequent rebuild in watch mode

lib/builder/builder.js

@@ -9,7 +9,7 @@ import { join, resolve, basename, extname, dirname } from 'path'
 import MFS from 'memory-fs'
 import webpackDevMiddleware from 'webpack-dev-middleware'
 import webpackHotMiddleware from 'webpack-hot-middleware'
-import { r, wp, wChunk, createRoutes, sequence, relativeTo, isPureObject, waitFor } from 'utils'
+import { r, wp, wChunk, createRoutes, sequence, relativeTo, isPureObject, waitFor, rmCache } from 'utils'
 import Debug from 'debug'
 import Glob from 'glob'
 import clientWebpackConfig from './webpack/client.config.js'
@@ -475,7 +475,11 @@ export default class Builder {
             /* istanbul ignore if */
             if (err) return reject(err)
             // not keep modified or deleted items in Vue.prototype
-            Object.keys(require.cache).forEach(key => !/\.node$/.test(key) && delete require.cache[key])
+            Object.keys(require.cache).forEach(key => {
+              if (!/(node_modules\/postcss)|(\.node$)/.test(key)) {
+                rmCache(key)
+              }
+            })
           })
         )
         return

lib/builder/webpack/base.config.js

@@ -19,7 +19,7 @@ export default function webpackBaseConfig({ name, isServer }) {
 
   const config = {
     name,
-    devtool: this.options.dev ? 'cheap-module-source-map' : false,
+    devtool: this.options.dev ? 'cheap-module-eval-source-map' : false,
     entry: {
       app: null
     },

lib/builder/webpack/server.config.js

@@ -23,7 +23,7 @@ export default function webpackServerConfig() {
   config = Object.assign(config, {
     target: 'node',
     node: false,
-    devtool: 'source-map',
+    devtool: this.options.dev ? config.devtool : 'source-map',
     entry: resolve(this.options.buildDir, 'server.js'),
     output: Object.assign({}, config.output, {
       filename: 'server-bundle.js',

lib/common/utils.js

@@ -268,3 +268,16 @@ export function createRoutes(files, srcDir) {
   })
   return cleanChildrenRoutes(routes)
 }
+
+export function rmCache(path) {
+  const mod = require.cache[path]
+  delete require.cache[path]
+  if (mod.parent && mod.parent.children) {
+    for (let i = 0; i < mod.parent.children.length; i++) {
+      if (mod.parent.children[i] === mod) {
+        mod.parent.children.splice(i, 1)
+        break
+      }
+    }
+  }
+}