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google-chromechromiumtrace

Load json manually in chrome://tracing

I have a trace events JSON data and I want to view it using chrome://tracing. However, I don’t want to load the JSON every time.

Is there a way I can pass the JSON data to chrome://tracing so that without manually clicking load data all my data gets loaded?

Solution

  • The Trace-viewer tool currently loads the JSON file in 3 ways:

    • When recording a new trace
    • When loading the file via the load button after the file has been picked
    • When dropping the file into the tab (drag & drop)

    All of these do a one-time update to the active trace.

    Technical details

    Look at the profiling_view and notice

     tr.ui.b.readFile(file).then(
 ...
    this.setActiveTrace(file.name, data);

    and a few variations on calls to setActiveTrace from beginRecording , onLoadClicked_ and dropHandler_ .

    Solution suggestions

    Yes, there are a few ways in which you can pass the json data to chrome://tracing (i.e. trace viewer) without manually clicking load data .

    Depending on how much effort you want to put into it:

    1. Don't manually click load but drag and drop the file
    2. Automate the drag & drop (example with selenium) based on a script which watches for file changes to the JSON
    3. Automate the load based on file changes
    4. Contribute to Trace Viewer yourself and add this feature. See the tracing ecosystem explainer and contributing. Note it is now part of the Catapult project in GitHub.

    See fswatch - a cross-platform file change monitor.