Add flag for preloading all server chunks (#64084)

This adds an experimental flag to allow testing preloading all server
chunks including webpack chunks during the server initialization. It is
disabled by default and only opt-in for experimenting.

Closes NEXT-3005

packages/next/src/server/config-schema.ts

@@ -236,6 +236,7 @@ export const configSchema: zod.ZodType<NextConfig> = z.lazy(() =>
     experimental: z
       .strictObject({
         appDocumentPreloading: z.boolean().optional(),
+        allServerChunksPreloading: z.boolean().optional(),
         adjustFontFallbacks: z.boolean().optional(),
         adjustFontFallbacksWithSizeAdjust: z.boolean().optional(),
         allowedRevalidateHeaderKeys: z.array(z.string()).optional(),

packages/next/src/server/config-shared.ts

@@ -184,6 +184,7 @@ export interface ExperimentalConfig {
   linkNoTouchStart?: boolean
   caseSensitiveRoutes?: boolean
   appDocumentPreloading?: boolean
+  allServerChunksPreloading?: boolean
   strictNextHead?: boolean
   clientRouterFilter?: boolean
   clientRouterFilterRedirects?: boolean
@@ -881,6 +882,7 @@ export const defaultConfig: NextConfig = {
     linkNoTouchStart: false,
     caseSensitiveRoutes: false,
     appDocumentPreloading: undefined,
+    allServerChunksPreloading: undefined,
     clientRouterFilter: true,
     clientRouterFilterRedirects: false,
     fetchCacheKeyPrefix: '',

packages/next/src/server/next-server.ts

@@ -228,6 +228,33 @@ export default class NextNodeServer extends BaseServer {
       }).catch(() => {})
     }
 
+    if (
+      !options.dev &&
+      this.nextConfig.experimental.allServerChunksPreloading
+    ) {
+      const appPathsManifest = this.getAppPathsManifest()
+      const pagesManifest = this.getPagesManifest()
+
+      for (const page of Object.keys(pagesManifest || {})) {
+        loadComponents({ distDir: this.distDir, page, isAppPath: false }).catch(
+          () => {}
+        )
+      }
+
+      for (const page of Object.keys(appPathsManifest || {})) {
+        loadComponents({ distDir: this.distDir, page, isAppPath: true })
+          .then(({ ComponentMod }) => {
+            const webpackRequire = ComponentMod.__next_app__.require
+            if (webpackRequire?.m) {
+              for (const id of Object.keys(webpackRequire.m)) {
+                webpackRequire(id)
+              }
+            }
+          })
+          .catch(() => {})
+      }
+    }
+
     if (!options.dev) {
       const { dynamicRoutes = [] } = this.getRoutesManifest() ?? {}
       this.dynamicRoutes = dynamicRoutes.map((r) => {