feat($core): debug to see performance

packages/@vuepress/cli/index.js

@@ -1,4 +1,4 @@
-const { chalk } = require('@vuepress/shared-utils')
+const { chalk, performance } = require('@vuepress/shared-utils')
 const semver = require('semver')
 
 try {
@@ -33,6 +33,8 @@ exports.bootstrap = function ({
   const { path, logger, env } = require('@vuepress/shared-utils')
   const { dev, build, eject } = require('@vuepress/core')
 
+  performance.start()
+
   cli
     .version(pkg.version)
     .help()

packages/@vuepress/core/lib/build.js

@@ -3,12 +3,11 @@
 module.exports = async function build (sourceDir, cliOptions = {}) {
   process.env.NODE_ENV = 'production'
 
-  const { path } = require('@vuepress/shared-utils')
   const webpack = require('webpack')
   const readline = require('readline')
   const escape = require('escape-html')
 
-  const { chalk, fs, logger, env } = require('@vuepress/shared-utils')
+  const { chalk, fs, path, logger, env, performance } = require('@vuepress/shared-utils')
   const prepare = require('./prepare/index')
   const createClientConfig = require('./webpack/createClientConfig')
   const createServerConfig = require('./webpack/createServerConfig')
@@ -83,6 +82,8 @@ module.exports = async function build (sourceDir, cliOptions = {}) {
   // DONE.
   const relativeDir = path.relative(cwd, outDir)
   logger.success(`${chalk.green('Success!')} Generated static files in ${chalk.cyan(relativeDir)}.\n`)
+  const { duration } = performance.stop()
+  logger.debug(`It took a total of ${duration}ms to run the ${chalk.cyan('vuepress build')}.`)
 
   // --- helpers ---
 

packages/@vuepress/core/lib/webpack/DevLogPlugin.js

@@ -4,7 +4,7 @@
  * Module dependencies.
  */
 
-const { chalk, logger } = require('@vuepress/shared-utils')
+const { chalk, logger, performance } = require('@vuepress/shared-utils')
 
 /**
  * Expose DevLogPlugin class.
@@ -35,7 +35,9 @@ module.exports = class DevLogPlugin {
       )
       if (isFirst) {
         isFirst = false
-        console.log(`\n${chalk.gray('>')} VuePress dev server listening at ${chalk.cyan(displayUrl)}`)
+        console.log(`${chalk.gray('>')} VuePress dev server listening at ${chalk.cyan(displayUrl)}`)
+        const { duration } = performance.stop()
+        logger.debug(`It took a total of ${duration}ms to run the ${chalk.cyan('vuepress dev')} for the first time.`)
       }
     })
     compiler.hooks.invalid.tap('vuepress-log', clearScreen)

packages/@vuepress/shared-utils/index.js

@@ -34,3 +34,5 @@ exports.fallback = require('./lib/fallback')
 exports.slugify = require('./lib/slugify')
 exports.tryChain = require('./lib/tryChain')
 exports.toAbsolutePath = require('./lib/toAbsolutePath')
+
+exports.performance = require('./lib/performance')

packages/@vuepress/shared-utils/lib/performance.js

@@ -0,0 +1,23 @@
+const os = require('os')
+
+class Performance {
+  constructor () {
+    this._totalMemory = os.totalmem()
+  }
+
+  start () {
+    this._startTime = Date.now()
+    this._startFreeMemory = os.freemem()
+  }
+
+  stop () {
+    this._endTime = Date.now()
+    this._endFreeMemory = os.freemem()
+    return {
+      duration: this._endTime - this._startTime,
+      memoryDiff: this._endFreeMemory - this._startFreeMemory
+    }
+  }
+}
+
+module.exports = new Performance()