Engine->Framework roll failing due to hot reload on Linux/Windows

[bdero]

Engine roll into Framework failed with (#89401), looks like a hot reload problem for windows and linux:

[LOG]:"[{"id":1,"result":{"code":1,"message":"hot reload failed to complete"}}]"

07:58 +16 ~2 -1: test\integration.shard\background_isolate_test.dart: Hot reload updates background isolates [E]                                                                                       
  Hot reload request failed
  
  [{"id":1,"result":{"code":1,"message":"hot reload failed to complete"}}]
  test\integration.shard\test_driver.dart 747:5             FlutterRunTestDriver._throwErrorResponse
  test\integration.shard\test_driver.dart 662:7             FlutterRunTestDriver._restart
  ===== asynchronous gap ===========================
  test\integration.shard\background_isolate_test.dart 84:5  main.<fn>
  

07:58 +16 ~2 -1: loading test\integration.shard\background_isolate_test.dart                                                                                                                           
Consider enabling the flag chain-stack-traces to receive more detailed exceptions.
For example, 'dart test --chain-stack-traces'.

Roll contains only a Dart SDK bump: https://dart.googlesource.com/sdk.git/+log/3e5ab8e22dc3..edf2936a5e06

Re-running the failed tests to verify that the failure's consistent, but suspecting we'll need to bisect this one.

[bdero]

Retries scheduled here:

• https://ci.chromium.org/ui/p/flutter/builders/try/Linux%20tool_integration_tests_1_4/4235/overview
• https://ci.chromium.org/ui/p/flutter/builders/try/Windows%20tool_integration_tests_1_5/3677/overview

@jason-simmons pointed out that dart-lang/sdk@57de39d looks potentially related due to involvement of background isolates/hot reload. /cc @mkustermann

[mkustermann]

@aam If you have time, could you look at this during MTV time today?

I think flutter/engine#26011 was the basic support, but there's still something missing for reload. I suspect it's mostly around removing some code.

If it cannot be fixed quickly in engine, it's also ok to revert for now.

[jason-simmons]

The test passes if I revert dart-lang/sdk@57de39d in a local build.

To reproduce it, patch https://github.com/flutter/flutter/blob/master/packages/flutter_tools/test/integration.shard/test_driver.dart#L106 to pass the local engine flags:

    _process = await _processManager.start(
      <String>[flutterBin]
        .followedBy(['--local-engine', 'host_debug_unopt'])
        .followedBy(arguments)
        .toList(),

Then run the test in the framework tree:

cd packages/flutter_tools
flutter test test/integration.shard/background_isolate_test.dart

[bdero]

Revert pending review: https://dart-review.googlesource.com/c/sdk/+/212345

[aam]

The issue seems to be caused by flutter_tools hot reload code attempting to reload all isolates (at once): and VM not handling it well: https://github.com/flutter/flutter/blob/master/packages/flutter_tools/lib/src/run_hot.dart#L1175

Generally speaking hot reload request has to be issued only to one isolate in an isolate group, reloading all isolates in the group is redundant. But we also need to tighten VM code to handle it better.

[bdero]

Engine roll is succeeding again after revert, so closing this one out.

[github-actions]

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