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doc: broken PerformanceObserver
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The code sample at the top of the "Performance measurements API" section of the docs does not run. The code in question: ```js const { PerformanceObserver, performance } = require('node:perf_hooks'); const obs = new PerformanceObserver((items) => { console.log(items.getEntries()[0].duration); performance.clearMarks(); }); obs.observe({ type: 'measure' }); performance.measure('Start to Now'); performance.mark('A'); doSomeLongRunningProcess(() => { performance.measure('A to Now', 'A'); performance.mark('B'); performance.measure('A to B', 'A', 'B'); }); ``` If you replace `doSomeLongRunningProcess` with an IIFE with a sleep() at the top of it, you get this: ```js const { PerformanceObserver, performance } = require('node:perf_hooks'); const obs = new PerformanceObserver((items) => { console.log(items.getEntries()[0].duration); performance.clearMarks(); }); obs.observe({ type: 'measure' }); performance.measure('Start to Now'); performance.mark('A'); (async function doSomeLongRunningProcess() { await new Promise(r => setTimeout(r, 5000)); performance.measure('A to Now', 'A'); performance.mark('B'); performance.measure('A to B', 'A', 'B'); })() ``` When you run this, you get the following output: ```sh $ node performance-test.js 17.873416 node:internal/per_context/domexception:53 ErrorCaptureStackTrace(this); ^ DOMException [SyntaxError]: The "A" performance mark has not been set at new DOMException (node:internal/per_context/domexception:53:5) at __node_internal_ (node:internal/util:695:10) at getMark (node:internal/perf/usertiming:65:11) at calculateStartDuration (node:internal/perf/usertiming:202:13) at measure (node:internal/perf/usertiming:220:7) at Performance.measure (node:internal/perf/performance:135:12) at /private/tmp/performance-test.js:14:15 Node.js v20.11.1 ``` I believe it's due to the call to `performance.clearMarks();` in the PerformanceObserver callback. If you remove that, it works as expected: ```js const { PerformanceObserver, performance } = require('node:perf_hooks'); const obs = new PerformanceObserver((items) => { console.log(items.getEntries()[0].duration); }); obs.observe({ type: 'measure' }); performance.measure('Start to Now'); performance.mark('A'); (async function doSomeLongRunningProcess() { await new Promise(r => setTimeout(r, 5000)); performance.measure('A to Now', 'A'); performance.mark('B'); performance.measure('A to B', 'A', 'B'); })() ``` ```sh $ node performance-test.js 17.761083 5002.468417 ```
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The code sample at the top of the "Performance measurements API" section of the docs does not run. The code in question: ```js const { PerformanceObserver, performance } = require('node:perf_hooks'); const obs = new PerformanceObserver((items) => { console.log(items.getEntries()[0].duration); performance.clearMarks(); }); obs.observe({ type: 'measure' }); performance.measure('Start to Now'); performance.mark('A'); doSomeLongRunningProcess(() => { performance.measure('A to Now', 'A'); performance.mark('B'); performance.measure('A to B', 'A', 'B'); }); ``` If you replace `doSomeLongRunningProcess` with an IIFE with a sleep() at the top of it, you get this: ```js const { PerformanceObserver, performance } = require('node:perf_hooks'); const obs = new PerformanceObserver((items) => { console.log(items.getEntries()[0].duration); performance.clearMarks(); }); obs.observe({ type: 'measure' }); performance.measure('Start to Now'); performance.mark('A'); (async function doSomeLongRunningProcess() { await new Promise(r => setTimeout(r, 5000)); performance.measure('A to Now', 'A'); performance.mark('B'); performance.measure('A to B', 'A', 'B'); })() ``` When you run this, you get the following output: ```sh $ node performance-test.js 17.873416 node:internal/per_context/domexception:53 ErrorCaptureStackTrace(this); ^ DOMException [SyntaxError]: The "A" performance mark has not been set at new DOMException (node:internal/per_context/domexception:53:5) at __node_internal_ (node:internal/util:695:10) at getMark (node:internal/perf/usertiming:65:11) at calculateStartDuration (node:internal/perf/usertiming:202:13) at measure (node:internal/perf/usertiming:220:7) at Performance.measure (node:internal/perf/performance:135:12) at /private/tmp/performance-test.js:14:15 Node.js v20.11.1 ``` I believe it's due to the call to `performance.clearMarks();` in the PerformanceObserver callback. If you remove that, it works as expected: ```js const { PerformanceObserver, performance } = require('node:perf_hooks'); const obs = new PerformanceObserver((items) => { console.log(items.getEntries()[0].duration); }); obs.observe({ type: 'measure' }); performance.measure('Start to Now'); performance.mark('A'); (async function doSomeLongRunningProcess() { await new Promise(r => setTimeout(r, 5000)); performance.measure('A to Now', 'A'); performance.mark('B'); performance.measure('A to B', 'A', 'B'); })() ``` ```sh $ node performance-test.js 17.761083 5002.468417 ``` PR-URL: nodejs#54227 Reviewed-By: Chengzhong Wu <legendecas@gmail.com>
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The code sample at the top of the "Performance measurements API" section of the docs does not run. The code in question: ```js const { PerformanceObserver, performance } = require('node:perf_hooks'); const obs = new PerformanceObserver((items) => { console.log(items.getEntries()[0].duration); performance.clearMarks(); }); obs.observe({ type: 'measure' }); performance.measure('Start to Now'); performance.mark('A'); doSomeLongRunningProcess(() => { performance.measure('A to Now', 'A'); performance.mark('B'); performance.measure('A to B', 'A', 'B'); }); ``` If you replace `doSomeLongRunningProcess` with an IIFE with a sleep() at the top of it, you get this: ```js const { PerformanceObserver, performance } = require('node:perf_hooks'); const obs = new PerformanceObserver((items) => { console.log(items.getEntries()[0].duration); performance.clearMarks(); }); obs.observe({ type: 'measure' }); performance.measure('Start to Now'); performance.mark('A'); (async function doSomeLongRunningProcess() { await new Promise(r => setTimeout(r, 5000)); performance.measure('A to Now', 'A'); performance.mark('B'); performance.measure('A to B', 'A', 'B'); })() ``` When you run this, you get the following output: ```sh $ node performance-test.js 17.873416 node:internal/per_context/domexception:53 ErrorCaptureStackTrace(this); ^ DOMException [SyntaxError]: The "A" performance mark has not been set at new DOMException (node:internal/per_context/domexception:53:5) at __node_internal_ (node:internal/util:695:10) at getMark (node:internal/perf/usertiming:65:11) at calculateStartDuration (node:internal/perf/usertiming:202:13) at measure (node:internal/perf/usertiming:220:7) at Performance.measure (node:internal/perf/performance:135:12) at /private/tmp/performance-test.js:14:15 Node.js v20.11.1 ``` I believe it's due to the call to `performance.clearMarks();` in the PerformanceObserver callback. If you remove that, it works as expected: ```js const { PerformanceObserver, performance } = require('node:perf_hooks'); const obs = new PerformanceObserver((items) => { console.log(items.getEntries()[0].duration); }); obs.observe({ type: 'measure' }); performance.measure('Start to Now'); performance.mark('A'); (async function doSomeLongRunningProcess() { await new Promise(r => setTimeout(r, 5000)); performance.measure('A to Now', 'A'); performance.mark('B'); performance.measure('A to B', 'A', 'B'); })() ``` ```sh $ node performance-test.js 17.761083 5002.468417 ``` PR-URL: #54227 Reviewed-By: Chengzhong Wu <legendecas@gmail.com>
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The code sample at the top of the "Performance measurements API" section of the docs does not run.
The code in question:
If you replace
doSomeLongRunningProcess
with an IIFE with a sleep() at the top of it, you get this:When you run this, you get the following output:
I believe it's due to the call to
performance.clearMarks();
in the PerformanceObserver callback. If you remove that, it works as expected: