GV

GeezerVison

The World Wide Web, restored to 800 pixels of glory.

Home|About|Gaming cabinet|Archives|How it works|Starter sites

On this site

  • Sign in
  • ActionsCI/CD and automation
  • CodespacesCloud development environments
  • All Features
  • Documentation
  • Training
  • Certifications
  • Build with Copilot
  • Customize Copilot
  • Integrations
  • Trending repos
  • GitHub Sponsors
  • Developer articles
  • Enterprises

This view

  • Original page
  • New address

GeezerVison is showing github.com — doc: add esm examples to node:trace_events · nodejs/node@ff8af58

File tree

Expand file treeCollapse file tree
Open diff view settings
Filter options
  • doc/api
    • tracing.md
Expand file treeCollapse file tree
Open diff view settings
Collapse file

‎doc/api/tracing.md‎

Copy file name to clipboardExpand all lines: doc/api/tracing.md
+102-19Lines changed: 102 additions & 19 deletions
  • Display the source diff
  • Display the rich diff
Original file line numberDiff line numberDiff line change
@@ -69,9 +69,19 @@ node --trace-event-categories v8,node,node.async_hooks
6969

7070
Alternatively, trace events may be enabled using the `node:trace_events` module:
7171

72-
```js
73-
const trace_events = require('node:trace_events');
74-
const tracing = trace_events.createTracing({ categories: ['node.perf'] });
72+
```mjs
73+
import { createTracing } from 'node:trace_events';
74+
const tracing = createTracing({ categories: ['node.perf'] });
75+
tracing.enable(); // Enable trace event capture for the 'node.perf' category
76+
77+
// do work
78+
79+
tracing.disable(); // Disable trace event capture for the 'node.perf' category
80+
```
81+
82+
```cjs
83+
const { createTracing } = require('node:trace_events');
84+
const tracing = createTracing({ categories: ['node.perf'] });
7585
tracing.enable(); // Enable trace event capture for the 'node.perf' category
7686

7787
// do work
@@ -153,20 +163,36 @@ Disables this `Tracing` object.
153163
Only trace event categories _not_ covered by other enabled `Tracing` objects
154164
and _not_ specified by the `--trace-event-categories` flag will be disabled.
155165

156-
```js
157-
const trace_events = require('node:trace_events');
158-
const t1 = trace_events.createTracing({ categories: ['node', 'v8'] });
159-
const t2 = trace_events.createTracing({ categories: ['node.perf', 'node'] });
166+
```mjs
167+
import { createTracing, getEnabledCategories } from 'node:trace_events';
168+
const t1 = createTracing({ categories: ['node', 'v8'] });
169+
const t2 = createTracing({ categories: ['node.perf', 'node'] });
170+
t1.enable();
171+
t2.enable();
172+
173+
// Prints 'node,node.perf,v8'
174+
console.log(getEnabledCategories());
175+
176+
t2.disable(); // Will only disable emission of the 'node.perf' category
177+
178+
// Prints 'node,v8'
179+
console.log(getEnabledCategories());
180+
```
181+
182+
```cjs
183+
const { createTracing, getEnabledCategories } = require('node:trace_events');
184+
const t1 = createTracing({ categories: ['node', 'v8'] });
185+
const t2 = createTracing({ categories: ['node.perf', 'node'] });
160186
t1.enable();
161187
t2.enable();
162188

163189
// Prints 'node,node.perf,v8'
164-
console.log(trace_events.getEnabledCategories());
190+
console.log(getEnabledCategories());
165191

166192
t2.disable(); // Will only disable emission of the 'node.perf' category
167193

168194
// Prints 'node,v8'
169-
console.log(trace_events.getEnabledCategories());
195+
console.log(getEnabledCategories());
170196
```
171197

172198
#### `tracing.enable()`
@@ -200,10 +226,19 @@ added: v10.0.0
200226

201227
Creates and returns a `Tracing` object for the given set of `categories`.
202228

203-
```js
204-
const trace_events = require('node:trace_events');
229+
```mjs
230+
import { createTracing } from 'node:trace_events';
231+
const categories = ['node.perf', 'node.async_hooks'];
232+
const tracing = createTracing({ categories });
233+
tracing.enable();
234+
// do stuff
235+
tracing.disable();
236+
```
237+
238+
```cjs
239+
const { createTracing } = require('node:trace_events');
205240
const categories = ['node.perf', 'node.async_hooks'];
206-
const tracing = trace_events.createTracing({ categories });
241+
const tracing = createTracing({ categories });
207242
tracing.enable();
208243
// do stuff
209244
tracing.disable();
@@ -226,23 +261,71 @@ Given the file `test.js` below, the command
226261
`node --trace-event-categories node.perf test.js` will print
227262
`'node.async_hooks,node.perf'` to the console.
228263

229-
```js
230-
const trace_events = require('node:trace_events');
231-
const t1 = trace_events.createTracing({ categories: ['node.async_hooks'] });
232-
const t2 = trace_events.createTracing({ categories: ['node.perf'] });
233-
const t3 = trace_events.createTracing({ categories: ['v8'] });
264+
```mjs
265+
import { createTracing, getEnabledCategories } from 'node:trace_events';
266+
const t1 = createTracing({ categories: ['node.async_hooks'] });
267+
const t2 = createTracing({ categories: ['node.perf'] });
268+
const t3 = createTracing({ categories: ['v8'] });
269+
270+
t1.enable();
271+
t2.enable();
272+
273+
console.log(getEnabledCategories());
274+
```
275+
276+
```cjs
277+
const { createTracing, getEnabledCategories } = require('node:trace_events');
278+
const t1 = createTracing({ categories: ['node.async_hooks'] });
279+
const t2 = createTracing({ categories: ['node.perf'] });
280+
const t3 = createTracing({ categories: ['v8'] });
234281

235282
t1.enable();
236283
t2.enable();
237284

238-
console.log(trace_events.getEnabledCategories());
285+
console.log(getEnabledCategories());
239286
```
240287

241288
## Examples
242289

243290
### Collect trace events data by inspector
244291

245-
```js
292+
```mjs
293+
import { Session } from 'node:inspector';
294+
const session = new Session();
295+
session.connect();
296+
297+
function post(message, data) {
298+
return new Promise((resolve, reject) => {
299+
session.post(message, data, (err, result) => {
300+
if (err)
301+
reject(new Error(JSON.stringify(err)));
302+
else
303+
resolve(result);
304+
});
305+
});
306+
}
307+
308+
async function collect() {
309+
const data = [];
310+
session.on('NodeTracing.dataCollected', (chunk) => data.push(chunk));
311+
session.on('NodeTracing.tracingComplete', () => {
312+
// done
313+
});
314+
const traceConfig = { includedCategories: ['v8'] };
315+
await post('NodeTracing.start', { traceConfig });
316+
// do something
317+
setTimeout(() => {
318+
post('NodeTracing.stop').then(() => {
319+
session.disconnect();
320+
console.log(data);
321+
});
322+
}, 1000);
323+
}
324+
325+
collect();
326+
```
327+
328+
```cjs
246329
'use strict';
247330

248331
const { Session } = require('inspector');

0 commit comments

Comments
0 (0)
You are visitor 01402503 — GeezerVison does not store the pages you look up.
Best viewed with Netscape Navigator 4.7 or Internet Explorer 6 at 800×600. No cookies required.