49 lines
1.7 KiB
Markdown
49 lines
1.7 KiB
Markdown
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# Frequently Asked Questions
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## How do I open trace in UI from command line?
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When collecting traces from the command line, a convenient way to open traces
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is to use the [open\_trace\_in\_ui script](/tools/open_trace_in_ui).
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This can be used as follows:
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```sh
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curl -OL https://github.com/google/perfetto/raw/master/tools/open_trace_in_ui
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chmod +x open_trace_in_ui
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./open_trace_in_ui -i /path/to/trace
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```
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If you already have a Perfetto checkout, the first two steps can be skipped.
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From the Perfetto root, run:
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```sh
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tools/open_trace_in_ui -i /path/to/trace
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```
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## Incorrectly displayed overlapping events in JSON trace
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NOTE: JSON is considered a legacy trace format and is supported on a best-effort
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basis.
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The Perfetto UI and trace processor do support overlapping B/E/X events, in
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compliance with the
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[JSON spec](https://docs.google.com/document/d/1CvAClvFfyA5R-PhYUmn5OOQtYMH4h6I0nSsKchNAySU/preview#heading=h.nso4gcezn7n1).
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As stated in the spec, events are only allowed to perfecty nest.
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Users are recommended to emit
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[TrackEvent](/docs/instrumentation/track-events.md)
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instead, Perfetto's native trace format. See
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[this guide](/docs/reference/synthetic-track-event.md) for how common JSON
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events can be represented using
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TrackEvent.
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## How can I use Perfetto tooling without instrumenting my program?
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A common problem is that users want to use Perfetto analysis and visualization
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tooling but they don't want to instrument their program. This can be because
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Perfetto is not a good fit for their use-case or because they may already have
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an existing tracing system.
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The recommended approach for this is to emit Perfetto's native TrackEvent proto
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format. A reference guide for this is available
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[here](/docs/reference/synthetic-track-event.md).
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