134 lines
4.1 KiB
Markdown
134 lines
4.1 KiB
Markdown
# contentTracing
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> Collect tracing data from Chromium's content module for finding performance
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bottlenecks and slow operations.
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Process: [Main](../glossary.md#main-process)
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This module does not include a web interface so you need to open
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`chrome://tracing/` in a Chrome browser and load the generated file to view the
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result.
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**Note:** You should not use this module until the `ready` event of the app
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module is emitted.
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```javascript
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const { app, contentTracing } = require('electron')
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app.on('ready', () => {
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const options = {
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categoryFilter: '*',
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traceOptions: 'record-until-full,enable-sampling'
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}
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contentTracing.startRecording(options, () => {
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console.log('Tracing started')
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setTimeout(() => {
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contentTracing.stopRecording('', (path) => {
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console.log('Tracing data recorded to ' + path)
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})
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}, 5000)
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})
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})
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```
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## Methods
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The `contentTracing` module has the following methods:
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### `contentTracing.getCategories(callback)`
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* `callback` Function
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* `categories` String[]
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Get a set of category groups. The category groups can change as new code paths
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are reached.
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Once all child processes have acknowledged the `getCategories` request the
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`callback` is invoked with an array of category groups.
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### `contentTracing.startRecording(options, callback)`
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* `options` ([TraceCategoriesAndOptions](structures/trace-categories-and-options.md) | [TraceConfig](structures/trace-config.md))
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* `callback` Function
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Start recording on all processes.
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Recording begins immediately locally and asynchronously on child processes
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as soon as they receive the EnableRecording request. The `callback` will be
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called once all child processes have acknowledged the `startRecording` request.
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### `contentTracing.stopRecording(resultFilePath, callback)`
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* `resultFilePath` String
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* `callback` Function
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* `resultFilePath` String
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Stop recording on all processes.
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Child processes typically cache trace data and only rarely flush and send
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trace data back to the main process. This helps to minimize the runtime overhead
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of tracing since sending trace data over IPC can be an expensive operation. So,
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to end tracing, we must asynchronously ask all child processes to flush any
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pending trace data.
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Once all child processes have acknowledged the `stopRecording` request,
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`callback` will be called with a file that contains the traced data.
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Trace data will be written into `resultFilePath` if it is not empty or into a
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temporary file. The actual file path will be passed to `callback` if it's not
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`null`.
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### `contentTracing.startMonitoring(options, callback)`
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* `options` Object
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* `categoryFilter` String
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* `traceOptions` String
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* `callback` Function
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Start monitoring on all processes.
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Monitoring begins immediately locally and asynchronously on child processes as
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soon as they receive the `startMonitoring` request.
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Once all child processes have acknowledged the `startMonitoring` request the
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`callback` will be called.
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### `contentTracing.stopMonitoring(callback)`
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* `callback` Function
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Stop monitoring on all processes.
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Once all child processes have acknowledged the `stopMonitoring` request the
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`callback` is called.
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### `contentTracing.captureMonitoringSnapshot(resultFilePath, callback)`
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* `resultFilePath` String
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* `callback` Function
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* `resultFilePath` String
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Get the current monitoring traced data.
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Child processes typically cache trace data and only rarely flush and send
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trace data back to the main process. This is because it may be an expensive
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operation to send the trace data over IPC and we would like to avoid unneeded
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runtime overhead from tracing. So, to end tracing, we must asynchronously ask
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all child processes to flush any pending trace data.
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Once all child processes have acknowledged the `captureMonitoringSnapshot`
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request the `callback` will be called with a file that contains the traced data.
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### `contentTracing.getTraceBufferUsage(callback)`
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* `callback` Function
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* `value` Number
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* `percentage` Number
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Get the maximum usage across processes of trace buffer as a percentage of the
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full state. When the TraceBufferUsage value is determined the `callback` is
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called.
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