When scrolling page size changes: "exception was thrown: Build scheduled during frame."

[DaveShuckerow]

Steps to Reproduce

In the leafy app, some types of UI configuration changes affect the length of a scrolling page. This will be triggered by a change in the state of some stateful widget.

When this happens in debug mode, the view freezes and the trace produces an error:
I/flutter : ══╡ EXCEPTION CAUGHT BY RENDERING LIBRARY ╞═════════════════════════════════════════════════════════
I/flutter : The following assertion was thrown during performLayout():
I/flutter : Build scheduled during frame.
...

Flutter Doctor

[✓] Flutter (on Linux, channel master)
• Framework revision fa52b45 (14 hours ago), 2016-09-25 19:30:44
• Engine revision 3551e7a
• Tools Dart version 1.20.0-dev.5.0

[✓] Android toolchain - develop for Android devices (Android SDK 23.0.2)
...

[✓] Atom - a lightweight development environment for Flutter
• flutter plugin version 0.2.5
• dartlang plugin version 0.6.39

Logs and Crash Reports

Happy to leave full reports with you if you wood like me to. I'm tracking this at b/31438182.

For more information about diagnosing and reporting Flutter bugs, please see https://flutter.io/bug-reports/.

[eseidelGoogle]

This is blocking customer:leafy. @Hixie

[Hixie]

If we need a quick hack to fix it @abarth or @HansMuller can probably just silence the assert somehow for now (I'm OOO today). I'm working on a longer-term fix but it'll take a while longer since it's tied up in the scrollable refactor.

[DaveShuckerow]

I think we can get by for now if the correct fix will be in within ~3-4 weeks. If it'll take longer than that, then having a stopgap might be useful.

In terms of priority, I'm more concerned with #6096 than this issue because that's introducing failures that require restarting the app.

[eseidelGoogle]

@Hixie is on it. customer: fast also reported this as one of their top issues today.

[Hixie]

Still working on the longer term fix, let me know if this becomes urgent and I'll just silence the assert temporarily.

[eseidelGoogle]

Spoke with @Hixie he says this will be fixed in a few weeks. If this is critical and a workaround is needed before then, please let us know and we can help. @DaveShuckerow @drewwarren

[drewwarren]

Our current target for a release build is at end of this month. This is critical and would need to be resolved/worked around before that release.

[Hixie]

Does the bug manifest in release builds?

[drewwarren]

I cannot replicate this bug in release builds. Only in slow mode. This does lower the severity to our team.

[Hixie]

there's a good chance #6310 will hide this on the short term anyway

[tvolkert]

Hixie, can you see if #6310 did in deed hide this?

[Hixie]

It should have, yes.

[Hixie]

I'm closing this on the basis that we believe it's been papered over.

[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.