Write JSON stats file in streaming fashion and omit chunks for brevity

lib/core-server/package.json

@@ -40,6 +40,7 @@
     "prepare": "node ../../scripts/prepare.js"
   },
   "dependencies": {
+    "@discoveryjs/json-ext": "^0.5.3",
     "@storybook/builder-webpack4": "6.4.0-alpha.32",
     "@storybook/core-client": "6.4.0-alpha.32",
     "@storybook/core-common": "6.4.0-alpha.32",

lib/core-server/src/utils/output-stats.ts

@@ -1,10 +1,10 @@
+import { stringifyStream } from '@discoveryjs/json-ext';
+import { logger } from '@storybook/node-logger';
 import chalk from 'chalk';
+import fs from 'fs-extra';
 import path from 'path';
-import { logger } from '@storybook/node-logger';
 import { Stats } from 'webpack';
 
-import fs from 'fs-extra';
-
 export async function outputStats(directory: string, previewStats?: any, managerStats?: any) {
   if (previewStats) {
     const filePath = await writeStats(directory, 'preview', previewStats as Stats);
@@ -18,6 +18,13 @@ export async function outputStats(directory: string, previewStats?: any, manager
 
 export const writeStats = async (directory: string, name: string, stats: Stats) => {
   const filePath = path.join(directory, `${name}-stats.json`);
-  await fs.outputFile(filePath, JSON.stringify(stats.toJson(), null, 2), 'utf8');
+  const { chunks, ...data } = stats.toJson(); // omit chunks, which is about half of the total data
+  await new Promise((resolve, reject) => {
+    stringifyStream(data, null, 2)
+      .on('error', reject)
+      .pipe(fs.createWriteStream(filePath))
+      .on('error', reject)
+      .on('finish', resolve);
+  });
   return filePath;
 };

lib/core-server/typings.d.ts

@@ -7,6 +7,7 @@ declare module '@storybook/theming/paths';
 declare module '@storybook/ui/paths';
 declare module 'better-opn';
 declare module '@storybook/ui';
+declare module '@discoveryjs/json-ext';
 
 declare module 'file-system-cache' {
   export interface Options {

yarn.lock

@@ -4092,6 +4092,13 @@ __metadata:
   languageName: node
   linkType: hard
 
+"@discoveryjs/json-ext@npm:^0.5.3":
+  version: 0.5.3
+  resolution: "@discoveryjs/json-ext@npm:0.5.3"
+  checksum: 73789df18a61dfd91d839b95c403af9ba32b897c5b419d9a724de588099ce6cefc379ada7617a77dad967b6a026927faa65f55154205cfe88da8c0fca3da2986
+  languageName: node
+  linkType: hard
+
 "@ember-data/rfc395-data@npm:^0.0.4":
   version: 0.0.4
   resolution: "@ember-data/rfc395-data@npm:0.0.4"
@@ -8007,6 +8014,7 @@ __metadata:
   version: 0.0.0-use.local
   resolution: "@storybook/core-server@workspace:lib/core-server"
   dependencies:
+    "@discoveryjs/json-ext": ^0.5.3
     "@storybook/builder-webpack4": 6.4.0-alpha.32
     "@storybook/builder-webpack5": 6.4.0-alpha.32
     "@storybook/core-client": 6.4.0-alpha.32