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e124b0ff7d
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: https://github.com/nodejs/node/pull/54227
Reviewed-By: Chengzhong Wu <legendecas@gmail.com>
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| .. | ||
| addons.md | ||
| assert.md | ||
| async_context.md | ||
| async_hooks.md | ||
| buffer.md | ||
| child_process.md | ||
| cli.md | ||
| cluster.md | ||
| console.md | ||
| corepack.md | ||
| crypto.md | ||
| debugger.md | ||
| deprecations.md | ||
| dgram.md | ||
| diagnostics_channel.md | ||
| dns.md | ||
| documentation.md | ||
| domain.md | ||
| embedding.md | ||
| errors.md | ||
| esm.md | ||
| events.md | ||
| fs.md | ||
| globals.md | ||
| http2.md | ||
| http.md | ||
| https.md | ||
| index.md | ||
| inspector.md | ||
| intl.md | ||
| module.md | ||
| modules.md | ||
| n-api.md | ||
| net.md | ||
| os.md | ||
| packages.md | ||
| path.md | ||
| perf_hooks.md | ||
| permissions.md | ||
| process.md | ||
| punycode.md | ||
| querystring.md | ||
| readline.md | ||
| repl.md | ||
| report.md | ||
| single-executable-applications.md | ||
| sqlite.md | ||
| stream.md | ||
| string_decoder.md | ||
| synopsis.md | ||
| test.md | ||
| timers.md | ||
| tls.md | ||
| tracing.md | ||
| tty.md | ||
| typescript.md | ||
| url.md | ||
| util.md | ||
| v8.md | ||
| vm.md | ||
| wasi.md | ||
| webcrypto.md | ||
| webstreams.md | ||
| worker_threads.md | ||
| zlib.md | ||