fixup! test(@angular/build): add library builder scaling benchmark suite

Reported benchmark results in csv file or json.

Author: dherges

scripts/benchmark.mts

@@ -49,13 +49,17 @@ function parseIntList(raw: string | number | undefined): number[] | undefined {
     .map((s) => Number(s.trim()));
 }
 
-async function runLibraryBuilderSubsystem(options: {
-  layout?: string;
-  count?: string;
-  depth?: string;
-  iterations?: string | number;
-  json?: boolean;
-}): Promise<number> {
+async function runLibraryBuilderSubsystem(
+  options: {
+    layout?: string;
+    count?: string;
+    depth?: string;
+    iterations?: string | number;
+    json?: boolean;
+    csv?: string | boolean;
+  },
+  cwd: string,
+): Promise<number> {
   if (options.layout !== undefined && options.layout !== 'flat' && options.layout !== 'deep') {
     // eslint-disable-next-line no-console
     console.error('Error: --layout must be "flat" or "deep", got "' + options.layout + '".');
@@ -97,12 +101,20 @@ async function runLibraryBuilderSubsystem(options: {
     return 1;
   }
 
+  if (options.csv !== undefined && (typeof options.csv !== 'string' || options.csv.length === 0)) {
+    // eslint-disable-next-line no-console
+    console.error('Error: --csv requires a file path, got "' + options.csv + '".');
+
+    return 1;
+  }
+
   const cliOptions: LibraryBuilderBenchmarkOptions = {
     layout: options.layout as LibraryBuilderBenchmarkOptions['layout'],
     count,
     depth,
     iterations,
     json: Boolean(options.json),
+    csv: options.csv !== undefined ? path.resolve(cwd, options.csv as string) : undefined,
   };
 
   const { exitCode } = await runLibraryBuilderBenchmarks(cliOptions);
@@ -167,7 +179,8 @@ Options (library-builder):
                              that would otherwise be derived from --count (the smallest
                              depth with 2^depth >= each target count).
   --iterations=<n>           Measured iterations (default: 3)
-  --json                     Output raw measurements as JSON
+  --json                     Output raw measurements as JSON to stdout
+  --csv=<path>               Write raw per-iteration measurements as CSV to <path>
 
   --help                     Show this help message
 `);
@@ -176,7 +189,7 @@ Options (library-builder):
   }
 
   if (targetSubsystem === 'library-builder') {
-    return runLibraryBuilderSubsystem(options);
+    return runLibraryBuilderSubsystem(options, _cwd);
   }
 
   if (targetSubsystem !== 'i18n') {

scripts/benchmarks/library-builder/README.md

@@ -94,7 +94,8 @@ pnpm admin benchmark library-builder [options]
 | `--count=<n,n,...>`     | Entry-point count targets, drives both layouts                                                       | `10,20,50,100,200,300,400,500,1000,2000` |
 | `--depth=<n,n,...>`     | **`layout=deep` only.** Explicit tree depths, overriding the depths otherwise derived from `--count` | derived from `--count`                   |
 | `--iterations=<n>`      | Measured iterations per size                                                                         | `3`                                      |
-| `--json`                | Output raw measurements as JSON                                                                      | N/A                                      |
+| `--json`                | Output raw per-iteration measurements as JSON to stdout                                              | N/A                                      |
+| `--csv=<path>`          | Write raw per-iteration measurements as CSV to `<path>`                                              | N/A (opt-in only)                        |
 
 > `--count` and `--depth` are not independent sweep axes for `layout=deep`: `--count` is translated
 > into depths (smallest `depth` with `2^depth >= n` per target, de-duplicated); `--depth` only
@@ -167,5 +168,10 @@ All 60 builds (10 sizes x 3 iterations x 2 layouts) completed with `status: "ok"
 - Dependencies between entry points.
 - Shared stylesheet tokens imported by multiple components.
 - Watch mode.
-- Peak memory (`ru_maxrss`) and CPU time (`ru_utime` + `ru_stime`) metrics per build, in addition to wall-clock build time.
+- Peak memory and CPU time metrics per build, in addition to wall-clock build time. Note:
+  `child.resourceUsage()` does **not** exist on Node's `ChildProcess` (only `process.resourceUsage()`
+  exists, and it reports the calling process's own usage, not a child's) -- the real path is
+  polling `/proc/<pid>/status` (`VmHWM`) and `/proc/<pid>/stat` (`utime`+`stime`) on a timer while
+  the build subprocess is alive, which is Linux-only and requires moving `buildOnce` off
+  `spawnSync` onto `spawn()` so a polling timer can interleave with the child's lifetime.
 - Library "taste" variants beyond plain flat/deep, e.g. flat/deep with inter-entry-point dependencies or shared SCSS tokens (currently out of scope, listed above).

scripts/benchmarks/library-builder/index.mts

@@ -15,13 +15,15 @@ import path from 'node:path';
 import { fileURLToPath } from 'node:url';
 import { type FixtureOptions, type Layout, generateFixture } from './fixtures.mts';
 import { type BuildMeasurement, buildOnce, checkBuilderIsBuilt, median } from './harness.mts';
+import { formatCsvReport, formatJsonReport } from './reporters.mts';
 
 export interface LibraryBuilderBenchmarkOptions {
   layout?: Layout;
   count?: number[];
   depth?: number[];
   iterations?: number;
   json?: boolean;
+  csv?: string;
 }
 
 const repoRoot = fileURLToPath(new URL('../../../', import.meta.url));
@@ -125,7 +127,15 @@ export async function runLibraryBuilderBenchmarks(
   const anyFailed = measurements.some((m) => m.status === 'fail');
   if (options.json) {
     // eslint-disable-next-line no-console
-    console.log(JSON.stringify(measurements, null, 2));
+    console.log(formatJsonReport(measurements));
+  }
+
+  if (options.csv) {
+    fs.writeFileSync(options.csv, formatCsvReport(measurements));
+    if (!options.json) {
+      // eslint-disable-next-line no-console
+      console.log('CSV written to: ' + options.csv);
+    }
   }
 
   return { measurements, exitCode: anyFailed ? 1 : 0 };

scripts/benchmarks/library-builder/reporters.mts

@@ -0,0 +1,25 @@
+/**
+ * @license
+ * Copyright Google LLC All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.dev/license
+ */
+
+// Pure output formatting for the library-builder benchmark's measurements. No console/file I/O
+// here -- `index.mts` owns deciding when and where to print or write what this module formats.
+
+import type { BuildMeasurement } from './harness.mts';
+
+export function formatJsonReport(measurements: BuildMeasurement[]): string {
+  return JSON.stringify(measurements, null, 2);
+}
+
+export function formatCsvReport(measurements: BuildMeasurement[]): string {
+  const header = 'layout,entryPoints,iteration,durationMs,status';
+  const rows = measurements.map((m) =>
+    [m.layout, m.entryPoints, m.iteration, m.durationMs.toFixed(2), m.status].join(','),
+  );
+
+  return [header, ...rows].join('\n') + '\n';
+}