Engine should eagerly call onBeginFrame after running Dart's main()

[Hixie]

There's no reason for us to wait. On average, waiting means we wait 8ms of startup time doing nothing.

[dragostis]

Is this bug still relevant?

Running

void main() {
  DateTime now = new DateTime.now();

  ui.window.onBeginFrame = (Duration timeStamp) {
    print(new DateTime.now().difference(now));
  };
}

consistently prints ~2ms.

[Hixie]

Weird. Why 2ms? I would have expected 0ms or an even spread from 0 to 16ms.

[Hixie]

I see a variety of numbers testing both release and debug on a Nexus 6.
Debug seems to be 0-16ms, release seems to be 11ms-100+ms.
Also, in release for some reason we seem to call onBeginFrame twice in quick succession.

In conclusion, this bug is still relevant. :-)

[jhirth]

Also, in release for some reason we seem to call onBeginFrame twice in quick succession.

On my device, it always starts with 2 window.onMetricsChanged calls where window.physicalSize is still 0x0.

Does that event also trigger a redraw?

[abarth]

Does that event also trigger a redraw?

By itself, that does not trigger a redraw, but it's common for code that's listening to that event to schedule a redraw.

[zoechi]

Is this issue still relevant?

[markusaksli-nc]

Engine doesn't seem to call this after Dart's main(). Can only get a print if I use runApp() at some point as well (but the duration is no longer useful then).

[chinmaygarde]

Today, frame scheduling begins eagerly as soon as the rasterizer is setup.

[github-actions]

This thread has been automatically locked since there has not been any recent activity after it was closed. If you are still experiencing a similar issue, please open a new bug, including the output of flutter doctor -v and a minimal reproduction of the issue.