[fix] prerender in subprocess

.changeset/witty-avocados-admire.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/kit': patch
+---
+
+[breaking] remove Prerendered.assets

packages/kit/rollup.config.js

@@ -61,9 +61,10 @@ export default [
 	{
 		input: {
 			cli: 'src/cli.js',
+			hooks: 'src/hooks.js',
 			node: 'src/node/index.js',
 			'node/polyfills': 'src/node/polyfills.js',
-			hooks: 'src/hooks.js',
+			prerender: 'src/core/prerender/prerender.js',
 			vite: 'src/vite/index.js'
 		},
 		output: {

packages/kit/src/core/prerender/prerender.js

@@ -1,18 +1,34 @@
 import { readFileSync, writeFileSync } from 'fs';
 import { dirname, join } from 'path';
+import sade from 'sade';
 import { pathToFileURL, URL } from 'url';
 import { mkdirp, posixify, walk } from '../../utils/filesystem.js';
 import { installPolyfills } from '../../node/polyfills.js';
 import { is_root_relative, resolve } from '../../utils/url.js';
 import { queue } from './queue.js';
 import { crawl } from './crawl.js';
 import { escape_html_attr } from '../../utils/escape.js';
+import { logger } from '../utils.js';
+import { load_config } from '../config/index.js';
 
 /**
  * @typedef {import('types').PrerenderErrorHandler} PrerenderErrorHandler
  * @typedef {import('types').Logger} Logger
  */
 
+const prog = sade('prerender');
+prog
+	.command('run', '', { default: true })
+	.describe('Runs prerendering. Only for internal use')
+	.option('--client_out_dir', "Vite's output directory", '')
+	.option('--results_path', 'Where to put the results', '')
+	.option('--manifest_path', "SvelteKit's manifest file", '')
+	.option('--verbose', 'Whether logging should be verbose', false)
+	.action(async (opts) => {
+		prerender(opts);
+	});
+prog.parse(process.argv, { unknown: (arg) => `Unknown option: ${arg}` });
+
 /**
  * @param {Parameters<PrerenderErrorHandler>[0]} details
  * @param {import('types').ValidatedKitConfig} config
@@ -49,15 +65,24 @@ function normalise_error_handler(log, config) {
 const OK = 2;
 const REDIRECT = 3;
 
+/**
+ * @param {string} path
+ * @param {import('types').Prerendered} prerendered
+ */
+const output_and_exit = (path, prerendered) => {
+	writeFileSync(path, JSON.stringify(prerendered));
+	process.exit(0);
+};
+
 /**
  * @param {{
- *   config: import('types').ValidatedKitConfig;
  *   client_out_dir: string;
+ *   results_path: string;
  *   manifest_path: string;
- *   log: Logger;
+ *   verbose: boolean;
  * }} opts
  */
-export async function prerender({ config, client_out_dir, manifest_path, log }) {
+export async function prerender({ client_out_dir, results_path, manifest_path, verbose }) {
 	/** @type {import('types').Prerendered} */
 	const prerendered = {
 		pages: new Map(),
@@ -66,10 +91,17 @@ export async function prerender({ config, client_out_dir, manifest_path, log })
 		paths: []
 	};
 
+	/** @type {import('types').ValidatedKitConfig} */
+	const config = (await load_config()).kit;
+
 	if (!config.prerender.enabled) {
-		return prerendered;
+		output_and_exit(results_path, prerendered);
+		return;
 	}
 
+	/** @type {import('types').Logger} */
+	const log = logger({ verbose });
+
 	installPolyfills();
 	const { fetch } = globalThis;
 	globalThis.fetch = async (info, init) => {
@@ -349,7 +381,7 @@ export async function prerender({ config, client_out_dir, manifest_path, log })
 	mkdirp(dirname(file));
 	writeFileSync(file, await rendered.text());
 
-	return prerendered;
+	output_and_exit(results_path, prerendered);
 }
 
 /** @return {string} */

packages/kit/src/vite/index.js

@@ -1,3 +1,4 @@
+import { spawnSync } from 'child_process';
 import fs from 'fs';
 import path from 'path';
 import colors from 'kleur';
@@ -7,7 +8,6 @@ import { mkdirp, posixify, rimraf } from '../utils/filesystem.js';
 import * as sync from '../core/sync/sync.js';
 import { build_server } from './build/build_server.js';
 import { build_service_worker } from './build/build_service_worker.js';
-import { prerender } from '../core/prerender/prerender.js';
 import { load_config } from '../core/config/index.js';
 import { dev } from './dev/index.js';
 import { generate_manifest } from '../core/generate_manifest/index.js';
@@ -273,9 +273,8 @@ function kit() {
 		 * then use this hook to kick off builds for the server and service worker.
 		 */
 		async writeBundle(_options, bundle) {
-			log = logger({
-				verbose: vite_config.logLevel === 'info'
-			});
+			const verbose = vite_config.logLevel === 'info';
+			log = logger({ verbose });
 
 			fs.writeFileSync(
 				`${paths.client_out_dir}/${svelte_config.kit.appDir}/version.json`,
@@ -320,12 +319,26 @@ function kit() {
 			process.env.SVELTEKIT_SERVER_BUILD_COMPLETED = 'true';
 			log.info('Prerendering');
 
-			prerendered = await prerender({
-				config: svelte_config.kit,
-				client_out_dir: vite_config.build.outDir,
-				manifest_path,
-				log
-			});
+			const results_path = `${svelte_config.kit.outDir}/generated/prerendered.json`;
+
+			// do prerendering in a subprocess so any dangling stuff gets killed upon completion
+			spawnSync(
+				'node',
+				[
+					'./node_modules/@sveltejs/kit/dist/prerender.js',
+					'--client_out_dir',
+					vite_config.build.outDir,
+					'--results_path',
+					results_path,
+					'--manifest_path',
+					manifest_path,
+					'--verbose',
+					'' + verbose
+				],
+				{ stdio: 'inherit' }
+			);
+
+			prerendered = JSON.parse(fs.readFileSync(results_path, 'utf8'));
 
 			if (options.service_worker_entry_file) {
 				if (svelte_config.kit.paths.assets) {
@@ -364,13 +377,6 @@ function kit() {
 					`See ${colors.bold().cyan('https://kit.svelte.dev/docs/adapters')} to learn how to configure your app to run on the platform of your choosing`
 				);
 			}
-
-			if (svelte_config.kit.prerender.enabled) {
-				// this is necessary to close any open db connections, etc.
-				// TODO: prerender in a subprocess so we can exit in isolation and then remove this
-				// https://github.com/sveltejs/kit/issues/5306
-				process.exit(0);
-			}
 		},
 
 		/**