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Comments (6)

aam avatar aam commented on May 21, 2024 1

Is it expected for send to fail in case the port is closed/not available?

No, it's not. Send should not behave differently whether port is open or closed. The underlying root cause of the exception is gap in the dart vm api Dart_NewSendPort/Dart_SendPortGetId that IsolateNameServer uses to keep track of opened send ports.

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iazel avatar iazel commented on May 21, 2024

After further analysis on Android, in case the main Activity is destroyed (i.e. AppLifecycleState.detached), even though the Isolate still runs in background, once we open back the app, port will be limited on sending data as if they didn't share the same codebase.

Notice that even if we get paused, the app will work without problems. It is only the detached state that causes problems.

This can be easily tested on Android by enabling Don't keep activities in Developer options settings.

Code sample:

import 'dart:async';
import 'dart:isolate';
import 'dart:ui';

import 'package:flutter/material.dart';

void main() {
    runApp(MyApp());
}

final class A {}

final class MyApp extends StatefulWidget {
  const MyApp({super.key});

  @override
  State<StatefulWidget> createState() {
    return _MyAppState();
  }
}

final class _MyAppState extends State<MyApp> {
  @override
  void initState() {
    super.initState();
    final port = IsolateNameServer.lookupPortByName('name');
    if (port == null) {
      Isolate.spawn((_) async {
        final port = ReceivePort();
        port.listen((message) {
          print('got $message');
        });
        IsolateNameServer.registerPortWithName(port.sendPort, 'name');
        var i = 0;
        while (true) {
          ++i;
          await Future<void>.delayed(const Duration(seconds: 5));
          print('looped $i times');
        }
      }, null);
    } else {
      port.send(A());
    }
  }

  @override
  Widget build(BuildContext context) {
    return const MaterialApp(
      home: Scaffold(
        body: Text('Hello World'),
      ),
    );
  }
}

By changing send to something like:

port.send('restarted');

It will work as expected.

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huycozy avatar huycozy commented on May 21, 2024

Thanks for the report. I also see the issue with the test and Don't keep activities on app as reported. This doesn't seem to belong to Android as I see the same test failed on macOS. Labeling the issue for engine team input.

flutter doctor -v (stable and master) 
[✓] Flutter (Channel stable, 3.19.6, on macOS 14.1 23B74 darwin-x64, locale en-VN)
    • Flutter version 3.19.6 on channel stable at /Users/huynq/Documents/GitHub/flutter
    • Upstream repository https://github.com/flutter/flutter.git
    • Framework revision 54e66469a9 (31 hours ago), 2024-04-17 13:08:03 -0700
    • Engine revision c4cd48e186
    • Dart version 3.3.4
    • DevTools version 2.31.1

[✓] Android toolchain - develop for Android devices (Android SDK version 34.0.0)
    • Android SDK at /Users/huynq/Library/Android/sdk
    • Platform android-34, build-tools 34.0.0
    • ANDROID_HOME = /Users/huynq/Library/Android/sdk
    • Java binary at: /Applications/Android Studio.app/Contents/jbr/Contents/Home/bin/java
    • Java version OpenJDK Runtime Environment (build 17.0.9+0-17.0.9b1087.7-11185874)
    • All Android licenses accepted.

[✓] Xcode - develop for iOS and macOS (Xcode 15.3)
    • Xcode at /Applications/Xcode15.3.app/Contents/Developer
    • Build 15E204a
    • CocoaPods version 1.15.2

[✓] Chrome - develop for the web
    • Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome

[✓] Android Studio (version 2023.2)
    • Android Studio at /Applications/Android Studio.app/Contents
    • Flutter plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/9212-flutter
    • Dart plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/6351-dart
    • android-studio-dir = /Applications/Android Studio.app/
    • Java version OpenJDK Runtime Environment (build 17.0.9+0-17.0.9b1087.7-11185874)

[✓] VS Code (version 1.88.1)
    • VS Code at /Applications/Visual Studio Code.app/Contents
    • Flutter extension version 3.86.0

[✓] Connected device (3 available)
    • RMX2001 (mobile) • EUYTFEUSQSRGDA6D • android-arm64  • Android 11 (API 30)
    • macOS (desktop)  • macos            • darwin-x64     • macOS 14.1 23B74 darwin-x64
    • Chrome (web)     • chrome           • web-javascript • Google Chrome 123.0.6312.124

[✓] Network resources
    • All expected network resources are available.

• No issues found!
[!] Flutter (Channel master, 3.22.0-18.0.pre.53, on macOS 14.1 23B74 darwin-x64, locale en-VN)
    • Flutter version 3.22.0-18.0.pre.53 on channel master at /Users/huynq/Documents/GitHub/flutter_master
    ! Warning: `flutter` on your path resolves to /Users/huynq/Documents/GitHub/flutter/bin/flutter, which is not inside your current Flutter SDK checkout at /Users/huynq/Documents/GitHub/flutter_master. Consider adding /Users/huynq/Documents/GitHub/flutter_master/bin to the front of your path.
    ! Warning: `dart` on your path resolves to /Users/huynq/Documents/GitHub/flutter/bin/dart, which is not inside your current Flutter SDK checkout at /Users/huynq/Documents/GitHub/flutter_master. Consider adding /Users/huynq/Documents/GitHub/flutter_master/bin to the front of your path.
    • Upstream repository https://github.com/flutter/flutter.git
    • Framework revision 098e7e7ff3 (2 hours ago), 2024-04-29 01:25:19 +0000
    • Engine revision 752b146df7
    • Dart version 3.5.0 (build 3.5.0-109.0.dev)
    • DevTools version 2.35.0-dev.16
    • If those were intentional, you can disregard the above warnings; however it is recommended to use "git" directly to perform update checks and upgrades.

[✓] Android toolchain - develop for Android devices (Android SDK version 34.0.0)
    • Android SDK at /Users/huynq/Library/Android/sdk
    • Platform android-34, build-tools 34.0.0
    • ANDROID_HOME = /Users/huynq/Library/Android/sdk
    • Java binary at: /Applications/Android Studio.app/Contents/jbr/Contents/Home/bin/java
    • Java version OpenJDK Runtime Environment (build 17.0.9+0-17.0.9b1087.7-11185874)
    • All Android licenses accepted.

[✓] Xcode - develop for iOS and macOS (Xcode 15.3)
    • Xcode at /Applications/Xcode15.3.app/Contents/Developer
    • Build 15E204a
    • CocoaPods version 1.15.2

[✓] Chrome - develop for the web
    • Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome

[✓] Android Studio (version 2023.2)
    • Android Studio at /Applications/Android Studio.app/Contents
    • Flutter plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/9212-flutter
    • Dart plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/6351-dart
    • android-studio-dir = /Applications/Android Studio.app/
    • Java version OpenJDK Runtime Environment (build 17.0.9+0-17.0.9b1087.7-11185874)

[✓] VS Code (version 1.88.1)
    • VS Code at /Applications/Visual Studio Code.app/Contents
    • Flutter extension version 3.86.0

[✓] Connected device (2 available)
    • macOS (desktop) • macos  • darwin-x64     • macOS 14.1 23B74 darwin-x64
    • Chrome (web)    • chrome • web-javascript • Google Chrome 124.0.6367.92

[✓] Network resources
    • All expected network resources are available.

! Doctor found issues in 1 category.

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a-siva avatar a-siva commented on May 21, 2024

//cc @aam

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aam avatar aam commented on May 21, 2024

The issue with original code #147469 (comment) is that registered isolate exits once it receives first message, so no further sends will work. It's confusing of course that the error talks about invalid object and only shows up if it's an instance of user-defined class being sent, it silently does nothing if primitive object is being sent.

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iazel avatar iazel commented on May 21, 2024

The issue with original code #147469 (comment) is that registered isolate exits once it receives first message, so no further sends will work. It's confusing of course that the error talks about invalid object and only shows up if it's an instance of user-defined class being sent, it silently does nothing if primitive object is being sent.

Yes, we exit the isolate just to showcase the diverging behaviour. Is it expected for send to fail in case the port is closed/not available?

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