refactor(@angular/build): avoid retaining worker file data for single-batch inlining

packages/angular/build/src/tools/esbuild/i18n-inliner-worker.ts

@@ -78,6 +78,12 @@ interface InlineFileBatchRequest {
    * The locale specifiers or locale objects that should be used during the inlining process of the file.
    */
   locales: (string | { locale: string; translation?: Blob })[];
+
+  /**
+   * Whether the file data should be treated as ephemeral and not cached long-term in the Worker.
+   * Typically true when all remaining locales for the file are processed in a single batch.
+   */
+  ephemeral?: boolean;
 }
 
 /**
@@ -124,23 +130,35 @@ const fileDataCache = new Map<string, Promise<CachedFileData>>();
 const deserializedTranslations = new Map<string, Promise<Record<string, unknown>>>();
 
 /**
- * Retrieves the cached file data for a filename, loading and extracting it on the first request.
+ * Retrieves the file data for a filename, loading and extracting localization metadata.
+ * If `cache` is true, the result is cached in `fileDataCache` across requests in this Worker.
+ * If `cache` is false (ephemeral), the result is not retained in `fileDataCache`, allowing it
+ * to be garbage-collected once the batch request finishes.
  *
  * @param filename The name of the file to load.
- * @returns The cached code and localization metadata.
+ * @param cache Whether to cache the loaded file data in the Worker's long-term cache.
+ * @returns The cached or newly extracted code and localization metadata.
  */
-function getFileData(filename: string): Promise<CachedFileData> {
-  let fileDataPromise = fileDataCache.get(filename);
-  if (!fileDataPromise) {
-    fileDataPromise = (async () => {
-      const data = files.get(filename);
-      assert(data !== undefined, `Invalid inline request for file '${filename}'.`);
-
-      const code = await data.text();
-      const metadata = extractLocalizeMetadata(filename, code);
-
-      return { code, metadata };
-    })();
+function loadFileData(filename: string, cache = true): Promise<CachedFileData> {
+  const existing = fileDataCache.get(filename);
+  if (existing) {
+    return existing;
+  }
+
+  const fileDataPromise = (async () => {
+    const data = files.get(filename);
+    assert(data !== undefined, `Invalid inline request for file '${filename}'.`);
+
+    const code = await data.text();
+    const metadata = extractLocalizeMetadata(filename, code);
+
+    return { code, metadata };
+  })();
+
+  if (cache) {
+    fileDataPromise.catch(() => {
+      fileDataCache.delete(filename);
+    });
     fileDataCache.set(filename, fileDataPromise);
   }
 
@@ -186,7 +204,7 @@ function loadTranslation(
  * @returns An object containing the inlined file and optional map content.
  */
 export default async function inlineFile(request: InlineFileRequest) {
-  const { code, metadata } = await getFileData(request.filename);
+  const { code, metadata } = await loadFileData(request.filename, true);
 
   // Sourcemaps are parsed on demand per request rather than cached long-term to prevent
   // monotonic memory growth as a worker processes multiple files across the build.
@@ -219,7 +237,7 @@ export default async function inlineFile(request: InlineFileRequest) {
 export async function inlineFileBatch(
   request: InlineFileBatchRequest,
 ): Promise<InlineFileBatchResult> {
-  const { code, metadata } = await getFileData(request.filename);
+  const { code, metadata } = await loadFileData(request.filename, !request.ephemeral);
 
   // Parse the sourcemap once for the entire batch.
   // It will naturally be garbage-collected after this batch action returns.

packages/angular/build/src/tools/esbuild/i18n-inliner.ts

@@ -9,7 +9,7 @@
 import assert from 'node:assert';
 import { extname, join } from 'node:path';
 import { serialize } from 'node:v8';
-import { calculateHash, createContentHash } from '../../utils/hash';
+import { calculateHash, createContentHash, initializeHash } from '../../utils/hash';
 import { WorkerPool } from '../../utils/worker-pool';
 import { type BuildOutputFile, BuildOutputFileType, createOutputFile } from './bundler-files';
 import { type PersistentCacheStore, createPersistentCacheStore } from './cache';
@@ -377,6 +377,7 @@ export class I18nInliner {
     const workerTasks: Promise<void>[] = [];
 
     for (const [filename, entries] of uncachedByFile) {
+      const ephemeral = entries.length <= localesPerBatch;
       for (let i = 0; i < entries.length; i += localesPerBatch) {
         const batchEntries = entries.slice(i, i + localesPerBatch);
         const task = (async () => {
@@ -387,6 +388,7 @@ export class I18nInliner {
                 locale: e.locale,
                 translation: e.translation,
               })),
+              ephemeral,
             },
             { name: 'inlineFileBatch' },
           )) as {
@@ -518,7 +520,11 @@ export class I18nInliner {
 
     // Initialize a persistent cache for i18n transformations.
     try {
-      this.#cache = await createPersistentCacheStore(join(persistentCachePath, 'angular-i18n'));
+      const [, cache] = await Promise.all([
+        initializeHash(),
+        createPersistentCacheStore(join(persistentCachePath, 'angular-i18n')),
+      ]);
+      this.#cache = cache;
     } catch {
       this.#cacheInitFailed = true;
 

packages/angular/build/src/tools/esbuild/i18n-inliner_spec.ts

@@ -10,6 +10,7 @@ import { transform } from 'esbuild';
 import fs from 'node:fs/promises';
 import os from 'node:os';
 import path from 'node:path';
+import { initializeHash } from '../../utils/hash';
 import { type BuildOutputFile, BuildOutputFileType, createOutputFile } from './bundler-files';
 import { I18nInliner } from './i18n-inliner';
 
@@ -43,6 +44,10 @@ function findFile(outputFiles: BuildOutputFile[], path: string): BuildOutputFile
 describe('I18nInliner', () => {
   let inliner: I18nInliner | undefined;
 
+  beforeAll(async () => {
+    await initializeHash();
+  });
+
   // A single thread is used throughout so that every file of every locale is inlined by the same
   // Worker. Any translation state that a Worker retains between requests is then observable.
   function createInliner(outputFiles: BuildOutputFile[]): I18nInliner {