55 lines
2.6 KiB
Markdown
55 lines
2.6 KiB
Markdown
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# Browser performance capture
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Start OpenChamber locally, then run:
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```bash
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bun run profile:browser
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```
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The command opens an isolated Chrome profile. On the first run, complete any
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login or setup in that window, prepare the sessions and screen you want to
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measure, then return to the terminal and press Enter. Use OpenChamber normally
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for the next 60 seconds.
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Google Chrome is selected first on macOS, with Chrome Canary and Chromium as
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fallbacks. Other Chromium-based browsers are used only when explicitly selected
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with `--chrome /path/to/executable`.
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The generated `artifacts/browser-profile-*/` directory contains:
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- `summary.json`: long-task, memory, network, sync-operation, and UI streaming/render metrics. `failedRequests` includes transport failures and HTTP 4xx/5xx responses, while `httpErrorResponses` isolates HTTP errors;
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- `trace.json`: import into Chrome DevTools Performance with **Load profile**;
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- `network.har`: import into Chrome DevTools Network with **Import HAR**.
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`summary.json.longTaskAttribution` correlates long tasks with global-session
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lifecycle publications, session navigation, and targeted sidebar/message-list
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renders. One task may appear under multiple marks when phases overlap.
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Chrome trace finalization is allowed up to two minutes for large captures. If
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Chrome still does not emit its completion event, the command preserves the
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summary, HAR, and all trace events received so far instead of discarding the
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entire recording. In that case `summary.json` sets `traceComplete` to `false`,
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and trace-derived long-task totals should be treated as lower bounds.
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Trace events are streamed to disk instead of being serialized into one large
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JavaScript string. Summary and HAR files are written first, so they remain
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available even if the trace file cannot be completed. `traceFileComplete`
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reports whether `trace.json` finished writing.
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The HAR omits response bodies and redacts cookies, authorization headers, and
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sensitive URL parameters. The trace applies the same key and URL-parameter
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redaction, but profiling artifacts can still reveal project paths and endpoint
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names. Do not publish them without review.
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The capture bypasses the PWA service worker and reloads without the browser cache before recording, so repeated optimization runs execute the current local build instead of a previously cached bundle. Network recording begins after that reload, so startup asset downloads are not included in the HAR totals.
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Useful options:
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```bash
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bun run profile:browser -- --duration 120
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bun run profile:browser -- --url http://localhost:4173
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bun run profile:browser -- --output /tmp/openchamber-profile
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```
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Run `bun run profile:browser -- --help` for all options.
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