test: make node:bench test samples survive a coarse clock

Most node:bench tests record a sample with `b.start();
process.hrtime.bigint(); b.end(1)`, counting on the extra clock read to
make end() see a later timestamp than start(). On a debian12-x64 CI
host the monotonic clock is coarse enough that all three reads returned
the same value, so end() threw ERR_INVALID_STATE ("insufficient clock
precision for benchmark sample") and test-bench-harness-errors failed;
every test using the idiom can fail the same way there.

Add test/common/bench.js with completeSample(), which spins until
process.hrtime.bigint() moves between start() and end(), and use it at
all of those sites, bench-runner fixtures included.

Signed-off-by: Shelley Vohr <shelley.vohr@gmail.com>
PR-URL: #65780
Fixes: #64226
Refs: #59146
Refs: #54534
Reviewed-By: Filip Skokan <panva.ip@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Gürgün Dayıoğlu <hey@gurgun.day>
Reviewed-By: Moshe Atlow <moshe@atlow.co.il>

Author: codebytere

test/common/README.md

@@ -28,6 +28,7 @@ several other tasks:
 ## Table of contents
 
 * [ArrayStream module](#arraystream-module)
+* [Bench module](#bench-module)
 * [Benchmark module](#benchmark-module)
 * [Child process module](#child-process-module)
 * [Common module API](#common-module-api)
@@ -49,6 +50,21 @@ several other tasks:
 * [UDP pair helper](#udp-pair-helper)
 * [WPT module](#wpt-module)
 
+## Bench module
+
+The `bench` module has helpers for tests of `node:bench`.
+
+### `completeSample(b[, operations[, options]])`
+
+* `b` The `BenchContext` passed to a `node:bench` benchmark function.
+* `operations` [\<number>][<number>] Passed to `b.end()`. **Default:** `1`.
+* `options` [\<Object>][<Object>] Passed to `b.end()`.
+* return the sample returned by `b.end()`.
+
+Calls `b.start()` and `b.end()` with at least one `process.hrtime.bigint()`
+tick in between, so the sample has a non-zero duration on hosts whose
+monotonic clock is coarse.
+
 ## Benchmark module
 
 The `benchmark` module is used by tests to run benchmarks.

test/common/bench.js

@@ -0,0 +1,13 @@
+'use strict';
+
+// Records a sample with start()/end() and at least one hrtime tick in
+// between, so its duration is non-zero even on hosts with a coarse clock.
+function completeSample(b, operations = 1, options = undefined) {
+  b.start();
+  const started = process.hrtime.bigint();
+  let now = started;
+  while (now === started) now = process.hrtime.bigint();
+  return b.end(operations, options);
+}
+
+module.exports = { completeSample };

test/fixtures/bench-runner/identity-child-a.cjs

@@ -1,11 +1,10 @@
 'use strict';
 
+const { completeSample } = require('../../common/bench');
 const { bench } = require('node:bench');
 
 module.exports = function declareChildA() {
   bench('child a', { samples: 1 }, (b) => {
-    b.start();
-    process.hrtime.bigint();
-    b.end(1);
+    completeSample(b);
   });
 };

test/fixtures/bench-runner/identity-child-b.cjs

@@ -1,11 +1,10 @@
 'use strict';
 
+const { completeSample } = require('../../common/bench');
 const { bench } = require('node:bench');
 
 module.exports = function declareChildB() {
   bench('child b', { samples: 1 }, (b) => {
-    b.start();
-    process.hrtime.bigint();
-    b.end(1);
+    completeSample(b);
   });
 };

test/fixtures/bench-runner/identity-preload.cjs

@@ -1,9 +1,8 @@
 'use strict';
 
+const { completeSample } = require('../../common/bench');
 const { bench } = require('node:bench');
 
 bench('preload identity', { samples: 1 }, (b) => {
-  b.start();
-  process.hrtime.bigint();
-  b.end(1);
+  completeSample(b);
 });

test/fixtures/bench-runner/identity-shared.cjs

@@ -1,11 +1,10 @@
 'use strict';
 
+const { completeSample } = require('../../common/bench');
 const { bench } = require('node:bench');
 
 module.exports = function registerSharedIdentity() {
   bench('shared identity', { samples: 1 }, (b) => {
-    b.start();
-    process.hrtime.bigint();
-    b.end(1);
+    completeSample(b);
   });
 };

test/fixtures/bench-runner/load-error-after-declaration.cjs

@@ -1,11 +1,10 @@
 'use strict';
 
+const { completeSample } = require('../../common/bench');
 const { bench } = require('node:bench');
 
 bench('declared before load error', { samples: 1 }, (b) => {
-  b.start();
-  process.hrtime.bigint();
-  b.end(1);
+  completeSample(b);
 });
 
 throw new Error('load failed after declaration');

test/fixtures/bench-runner/tools.cjs

@@ -1,5 +1,6 @@
 'use strict';
 
+const { completeSample } = require('../../common/bench');
 const { bench } = require('node:bench');
 
 if (process.env.NODE_BENCH_PID_LOG !== undefined) {
@@ -10,11 +11,5 @@ if (process.env.NODE_BENCH_PID_LOG !== undefined) {
 for (const size of [1, 2]) {
   bench('tools/simple.js', {
     params: { method: 'loop', size },
-  }, (b) => {
-    let value = 0;
-    b.start();
-    for (let i = 0; i < 1_000; i++) value += size;
-    b.end(1_000);
-    if (value === 0) throw new Error('unreachable');
-  });
+  }, (b) => completeSample(b, 1_000));
 }

test/parallel/test-bench-context-control.js

@@ -2,6 +2,7 @@
 'use strict';
 
 const common = require('../common');
+const { completeSample } = require('../common/bench');
 const assert = require('assert');
 const { createRunner } = require('node:bench');
 
@@ -16,9 +17,7 @@ const { createRunner } = require('node:bench');
   }, common.mustCall((b) => {
     invocations.push(`${b.phase}:${b.index}`);
     const detail = { index: b.index, phase: b.phase };
-    b.start();
-    process.hrtime.bigint();
-    const sample = b.end(2, { detail });
+    const sample = completeSample(b, 2, { detail });
     detail.index = -1;
 
     assert.strictEqual(sample.operations, 2);

test/parallel/test-bench-context-errors.js

@@ -2,15 +2,14 @@
 'use strict';
 
 const common = require('../common');
+const { completeSample } = require('../common/bench');
 const assert = require('assert');
 const { createRunner } = require('node:bench');
 
 const runner = createRunner({ yieldBetweenSamples: false });
 
 runner.bench('done during warmup', { samples: 1, warmup: 1 }, (b) => {
-  b.start();
-  process.hrtime.bigint();
-  b.end(1);
+  completeSample(b);
   b.done();
 });
 runner.bench('invalid record', { samples: 1 }, (b) => b.record(null));