feat(build,dev): add --profile support

packages/nuxi/bin/nuxi.mjs

@@ -1,5 +1,6 @@
 #!/usr/bin/env node
 
+import inspector from 'node:inspector'
 import nodeModule from 'node:module'
 import process from 'node:process'
 import { fileURLToPath } from 'node:url'
@@ -23,6 +24,22 @@ globalThis.__nuxt_cli__ = {
   startTime: Date.now(),
   entry: fileURLToPath(import.meta.url),
   devEntry: fileURLToPath(new URL('../dist/dev/index.mjs', import.meta.url)),
+  cpuProfileSession: undefined,
+}
+
+if (
+  process.argv.includes('--profile')
+  || process.argv.some(a => a.startsWith('--profile='))
+) {
+  const session = new inspector.Session()
+  session.connect()
+  // eslint-disable-next-line antfu/no-top-level-await
+  await new Promise((resolve) => {
+    session.post('Profiler.enable', () => {
+      session.post('Profiler.start', resolve)
+    })
+  })
+  globalThis.__nuxt_cli__.cpuProfileSession = session
 }
 
 // eslint-disable-next-line antfu/no-top-level-await

packages/nuxi/src/commands/_shared.ts

@@ -40,6 +40,15 @@ export const extendsArgs = {
   },
 } as const satisfies Record<string, ArgDef>
 
+export const profileArgs = {
+  profile: {
+    type: 'string',
+    description: 'Profile performance. Use --profile for CPU only, --profile=verbose for full report.',
+    default: undefined as string | undefined,
+    valueHint: 'verbose',
+  },
+} as const satisfies Record<string, ArgDef>
+
 export const legacyRootDirArgs = {
   // cwd falls back to rootDir's default (indirect default)
   cwd: {

packages/nuxi/src/commands/build.ts

@@ -10,7 +10,8 @@ import { overrideEnv } from '../utils/env'
 import { clearBuildDir } from '../utils/fs'
 import { loadKit } from '../utils/kit'
 import { logger } from '../utils/logger'
-import { cwdArgs, dotEnvArgs, envNameArgs, extendsArgs, legacyRootDirArgs, logLevelArgs } from './_shared'
+import { startCpuProfile, stopCpuProfile } from '../utils/profile'
+import { cwdArgs, dotEnvArgs, envNameArgs, extendsArgs, legacyRootDirArgs, logLevelArgs, profileArgs } from './_shared'
 
 export default defineCommand({
   meta: {
@@ -31,74 +32,98 @@ export default defineCommand({
     ...dotEnvArgs,
     ...envNameArgs,
     ...extendsArgs,
+    ...profileArgs,
     ...legacyRootDirArgs,
   },
   async run(ctx) {
     overrideEnv('production')
 
     const cwd = resolve(ctx.args.cwd || ctx.args.rootDir)
 
-    intro(colors.cyan('Building Nuxt for production...'))
+    const profileArg = ctx.args.profile
+    const perfValue = profileArg === 'verbose' ? true : profileArg ? 'quiet' : undefined
+    if (profileArg) {
+      await startCpuProfile()
+    }
+
+    try {
+      intro(colors.cyan('Building Nuxt for production...'))
 
-    const kit = await loadKit(cwd)
+      const kit = await loadKit(cwd)
 
-    await showVersions(cwd, kit, ctx.args.dotenv)
-    const nuxt = await kit.loadNuxt({
-      cwd,
-      dotenv: {
+      await showVersions(cwd, kit, ctx.args.dotenv)
+
+      const nuxt = await kit.loadNuxt({
         cwd,
-        fileName: ctx.args.dotenv,
-      },
-      envName: ctx.args.envName, // c12 will fall back to NODE_ENV
-      overrides: {
-        logLevel: ctx.args.logLevel as 'silent' | 'info' | 'verbose',
-        // TODO: remove in 3.8
-        _generate: ctx.args.prerender,
-        nitro: {
-          static: ctx.args.prerender,
-          preset: ctx.args.preset || process.env.NITRO_PRESET || process.env.SERVER_PRESET,
+        dotenv: {
+          cwd,
+          fileName: ctx.args.dotenv,
+        },
+        envName: ctx.args.envName, // c12 will fall back to NODE_ENV
+        overrides: {
+          logLevel: ctx.args.logLevel as 'silent' | 'info' | 'verbose',
+          // TODO: remove in 3.8
+          _generate: ctx.args.prerender,
+          nitro: {
+            static: ctx.args.prerender,
+            preset: ctx.args.preset || process.env.NITRO_PRESET || process.env.SERVER_PRESET,
+          },
+          ...(ctx.args.extends && { extends: ctx.args.extends }),
+          ...ctx.data?.overrides,
+          ...((perfValue || ctx.data?.overrides?.debug) && {
+            debug: {
+              ...ctx.data?.overrides?.debug,
+              ...(perfValue && { perf: perfValue }),
+            },
+          }),
         },
-        ...(ctx.args.extends && { extends: ctx.args.extends }),
-        ...ctx.data?.overrides,
-      },
-    })
+      })
 
-    let nitro: ReturnType<typeof kit.useNitro> | undefined
-    // In Bridge, if Nitro is not enabled, useNitro will throw an error
-    try {
-      // Use ? for backward compatibility for Nuxt <= RC.10
-      nitro = kit.useNitro?.()
-      if (nitro) {
-        logger.info(`Nitro preset: ${colors.cyan(nitro.options.preset)}`)
+      let nitro: ReturnType<typeof kit.useNitro> | undefined
+      // In Bridge, if Nitro is not enabled, useNitro will throw an error
+      try {
+        // Use ? for backward compatibility for Nuxt <= RC.10
+        nitro = kit.useNitro?.()
+        if (nitro) {
+          logger.info(`Nitro preset: ${colors.cyan(nitro.options.preset)}`)
+        }
+      }
+      catch {
+        //
       }
-    }
-    catch {
-      //
-    }
 
-    await clearBuildDir(nuxt.options.buildDir)
+      await clearBuildDir(nuxt.options.buildDir)
 
-    await kit.writeTypes(nuxt)
+      await kit.writeTypes(nuxt)
 
-    nuxt.hook('build:error', (err) => {
-      logger.error(`Nuxt build error: ${err}`)
-      process.exit(1)
-    })
+      nuxt.hook('build:error', async (err) => {
+        logger.error(`Nuxt build error: ${err}`)
+        if (profileArg) {
+          await stopCpuProfile(cwd, 'build')
+        }
+        process.exit(1)
+      })
 
-    await kit.buildNuxt(nuxt)
+      await kit.buildNuxt(nuxt)
 
-    if (ctx.args.prerender) {
-      if (!nuxt.options.ssr) {
-        logger.warn(`HTML content not prerendered because ${colors.cyan('ssr: false')} was set.`)
-        logger.info(`You can read more in ${colors.cyan('https://nuxt.com/docs/getting-started/deployment#static-hosting')}.`)
+      if (ctx.args.prerender) {
+        if (!nuxt.options.ssr) {
+          logger.warn(`HTML content not prerendered because ${colors.cyan('ssr: false')} was set.`)
+          logger.info(`You can read more in ${colors.cyan('https://nuxt.com/docs/getting-started/deployment#static-hosting')}.`)
+        }
+        // TODO: revisit later if/when nuxt build --prerender will output hybrid
+        const dir = nitro?.options.output.publicDir
+        const publicDir = dir ? relative(process.cwd(), dir) : '.output/public'
+        outro(`✨ You can now deploy ${colors.cyan(publicDir)} to any static hosting!`)
+      }
+      else {
+        outro('✨ Build complete!')
       }
-      // TODO: revisit later if/when nuxt build --prerender will output hybrid
-      const dir = nitro?.options.output.publicDir
-      const publicDir = dir ? relative(process.cwd(), dir) : '.output/public'
-      outro(`✨ You can now deploy ${colors.cyan(publicDir)} to any static hosting!`)
     }
-    else {
-      outro('✨ Build complete!')
+    finally {
+      if (profileArg) {
+        await stopCpuProfile(cwd, 'build')
+      }
     }
   },
 })

packages/nuxi/src/commands/dev.ts

@@ -13,7 +13,7 @@ import { isBun, isTest } from 'std-env'
 import { initialize } from '../dev'
 import { ForkPool } from '../dev/pool'
 import { debug, logger } from '../utils/logger'
-import { cwdArgs, dotEnvArgs, envNameArgs, extendsArgs, legacyRootDirArgs, logLevelArgs } from './_shared'
+import { cwdArgs, dotEnvArgs, envNameArgs, extendsArgs, legacyRootDirArgs, logLevelArgs, profileArgs } from './_shared'
 
 const startTime: number | undefined = Date.now()
 const forkSupported = !isTest && (!isBun || isBunForkSupported())
@@ -62,6 +62,7 @@ const command = defineCommand({
       },
       clipboard: { ...listhenArgs.clipboard, default: false },
     },
+    ...profileArgs,
     sslCert: {
       type: 'string',
       description: '(DEPRECATED) Use `--https.cert` instead.',
@@ -84,7 +85,8 @@ const command = defineCommand({
       showBanner: true,
     })
 
-    if (!ctx.args.fork) {
+    // Disable forking when profiling to capture all activity in one process
+    if (!ctx.args.fork || ctx.args.profile) {
       return {
         listener,
         close,

packages/nuxi/src/commands/generate.ts

@@ -1,6 +1,6 @@
 import { defineCommand } from 'citty'
 
-import { cwdArgs, dotEnvArgs, envNameArgs, extendsArgs, legacyRootDirArgs, logLevelArgs } from './_shared'
+import { cwdArgs, dotEnvArgs, envNameArgs, extendsArgs, legacyRootDirArgs, logLevelArgs, profileArgs } from './_shared'
 import buildCommand from './build'
 
 export default defineCommand({
@@ -18,6 +18,7 @@ export default defineCommand({
     ...dotEnvArgs,
     ...envNameArgs,
     ...extendsArgs,
+    ...profileArgs,
     ...legacyRootDirArgs,
   },
   async run(ctx) {

packages/nuxi/src/dev/index.ts

@@ -5,6 +5,7 @@ import type { NuxtDevContext, NuxtDevIPCMessage, NuxtParentIPCMessage } from './
 import process from 'node:process'
 import defu from 'defu'
 import { overrideEnv } from '../utils/env.ts'
+import { startCpuProfile, stopCpuProfile } from '../utils/profile.ts'
 import { NuxtDevServer } from './utils'
 
 const start = Date.now()
@@ -55,11 +56,22 @@ interface InitializeReturn {
 export async function initialize(devContext: NuxtDevContext, ctx: InitializeOptions = {}): Promise<InitializeReturn> {
   overrideEnv('development')
 
+  const profileArg = devContext.args.profile
+  const perfValue = profileArg === 'verbose' ? true : profileArg ? 'quiet' : undefined
+  const perfOverrides = perfValue
+    ? { debug: { perf: perfValue } } as NuxtConfig
+    : {}
+
+  if (profileArg) {
+    await startCpuProfile()
+  }
+
   const devServer = new NuxtDevServer({
     cwd: devContext.cwd,
     overrides: defu(
       ctx.data?.overrides,
       ({ extends: devContext.args.extends } satisfies NuxtConfig) as NuxtConfig,
+      perfOverrides,
     ),
     logLevel: devContext.args.logLevel as 'silent' | 'info' | 'verbose',
     clear: devContext.args.clear,
@@ -107,6 +119,17 @@ export async function initialize(devContext: NuxtDevContext, ctx: InitializeOpti
     console.debug(`Dev server (internal) initialized in ${Date.now() - start}ms`)
   }
 
+  if (profileArg) {
+    for (const signal of [
+      'exit',
+      'SIGTERM' /* Graceful shutdown */,
+      'SIGINT' /* Ctrl-C */,
+      'SIGQUIT' /* Ctrl-\ */,
+    ] as const) {
+      process.once(signal, () => stopCpuProfile(devContext.cwd, 'dev'))
+    }
+  }
+
   return {
     listener: devServer.listener,
     close: async () => {

packages/nuxi/src/dev/utils.ts

@@ -48,6 +48,7 @@ export interface NuxtDevContext {
     dotenv?: string
     envName?: string
     extends?: string
+    profile?: string | boolean
   }
 }
 

packages/nuxi/src/utils/profile.ts

@@ -0,0 +1,91 @@
+import type { Session } from 'node:inspector'
+import { mkdirSync, writeFileSync } from 'node:fs'
+import process from 'node:process'
+import { box } from '@clack/prompts'
+import { colors } from 'consola/utils'
+import { join, relative } from 'pathe'
+import { themeColor } from './ascii'
+
+let session: Session | undefined
+let profileCount = 0
+
+export async function startCpuProfile(): Promise<void> {
+  const cli = globalThis.__nuxt_cli__
+  if (cli?.cpuProfileSession) {
+    session = cli.cpuProfileSession
+    delete cli.cpuProfileSession
+    return
+  }
+  const inspector = await import('node:inspector')
+  session = new inspector.Session()
+  session.connect()
+  try {
+    await new Promise<void>((res, rej) => {
+      session!.post('Profiler.enable', (err) => {
+        if (err) {
+          return rej(err)
+        }
+        session!.post('Profiler.start', (err) => {
+          if (err) {
+            return rej(err)
+          }
+          res()
+        })
+      })
+    })
+  }
+  catch (err) {
+    session.disconnect()
+    session = undefined
+    throw err
+  }
+}
+
+export async function stopCpuProfile(outDir: string, command: string): Promise<string | undefined> {
+  if (!session) {
+    return
+  }
+  const s = session
+  session = undefined
+  const count = profileCount++
+  const outPath = join(outDir, `nuxt-${command}${count ? `-${count}` : ''}.cpuprofile`)
+  const relativeOutPath = relative(process.cwd(), outPath).replace(/^(?![^.]{1,2}\/)/, './')
+  try {
+    await new Promise<any>((resolve, reject) => {
+      s.post('Profiler.stop', (err, params) => {
+        if (err) {
+          return reject(err)
+        }
+
+        if (!params?.profile) {
+          return resolve(params)
+        }
+
+        try {
+          mkdirSync(outDir, { recursive: true })
+          writeFileSync(outPath, JSON.stringify(params.profile))
+          const nextSteps = [
+            `CPU profile written to ${colors.cyan(relativeOutPath)}.`,
+            `Open it in a CPU profile viewer like your IDE, or ${colors.cyan('https://discoveryjs.github.io/cpupro')}.`,
+          ]
+          box(`\n${nextSteps.map(step => ` › ${step}`).join('\n')}\n`, '', {
+            contentAlign: 'left',
+            titleAlign: 'left',
+            width: 'auto',
+            titlePadding: 2,
+            contentPadding: 2,
+            rounded: true,
+            withGuide: false,
+            formatBorder: (text: string) => `${themeColor + text}\x1B[0m`,
+          })
+        }
+        catch {}
+
+        resolve(params)
+      })
+    })
+  }
+  finally {
+    s.disconnect()
+  }
+}