Steps to reproduce Run the Isolate example <div class="snippet

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Unhandled Exception: Binding has not yet been initialized - when running Isolate sample example about flutter HOT 4 CLOSED

shashkiranr commented on June 23, 2024

Unhandled Exception: Binding has not yet been initialized - when running Isolate sample example

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Comments (4)

jonahwilliams commented on June 23, 2024 1

The sample code loads the string outside of the isolate and passes it in. There should be no copies with strings, so that should work ok.

Closing as this is not a bug or regression.

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huycozy commented on June 23, 2024

Hi @shashkiranr
I think you are hitting a similar issue at #130570 that calls platform channel in isolate, please see:

flutter/packages/flutter/lib/src/services/asset_bundle.dart

Lines 315 to 320 in 859a5ab

 class PlatformAssetBundle extends CachingAssetBundle { 

 @override 

 Future<ByteData> load(String key) { 

 final Uint8List encoded = utf8.encode(Uri(path: Uri.encodeFull(key)).path); 

 final Future<ByteData>? future = ServicesBinding.instance.defaultBinaryMessenger.send( 

 'flutter/assets',

It's marked as a duplicate of #119207. So I'm going to close the issue in favor of this one. Please follow up on it for updates.

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shashkiranr commented on June 23, 2024

I am not using any Platform Channels. Its a basic example of running Isolates from the main function. So you are telling me I can't run the sample isolate example?

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huycozy commented on June 23, 2024

I am not using any Platform Channels.

The rootBundle does, that's why I quoted the code above. The defaultBinaryMessenger will send a binary message to the platform plugins on the given channel:

flutter/packages/flutter/lib/src/services/binary_messenger.dart

Lines 56 to 60 in 66d1872

 /// Send a binary message to the platform plugins on the given channel. 

  /// 

  /// Returns a [Future] which completes to the received response, undecoded, 

  /// in binary form. 

  Future<ByteData?>? send(String channel, ByteData? message);

You can compare this with a different process like in the sample code below which does I/O task (write to file), the isolate works as expected in this case but reading assets task does not.

Sample code

import 'dart:convert';
import 'dart:io';

import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:flutter/foundation.dart';
import 'package:path_provider/path_provider.dart';

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  // final jsonData = await Isolate.run(() => _readAndParseJson(filename));
  // print('Number of JSON keys: ${jsonData.length}');
  runApp(const MyApp());
}

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

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        colorScheme: ColorScheme.fromSeed(seedColor: Colors.deepPurple),
        useMaterial3: true,
      ),
      home: const MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  const MyHomePage({super.key, required this.title});

  final String title;

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  int usingTime = 0;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        backgroundColor: Theme.of(context).colorScheme.inversePrimary,
        title: Text(widget.title),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Text("Running time: $usingTime ms"),
            TextButton(onPressed: _runWithIsolate, child: const Text("Run with isolate")),
            TextButton(
                onPressed: _runWithIsolateInPlatformChannel,
                child: const Text("Run with isolate in platform channel")),
          ],
        ),
      ),
    );
  }

  void _runWithIsolate() async {
    var savePath = await getTemporaryDirectory();
    var duration = await compute((path) => _runTask(path), "${savePath.path}/test.log");
    print('With isolate duration: $duration');
    if (mounted) {
      setState(() {
        usingTime = duration;
      });
    }
  }

  static int _runTask(String savePath) {
    var file = File(savePath);
    if (file.existsSync()) {
      file.deleteSync();
    }
    file = File(savePath);
    var startTime = DateTime.now().millisecondsSinceEpoch;
    for (var i = 0; i < 100; i++) {
      file.writeAsStringSync("a\n", mode: FileMode.append);
    }
    return DateTime.now().millisecondsSinceEpoch - startTime;
  }

  void _runWithIsolateInPlatformChannel() async {
    // final jsonData = await Isolate.run(() => _readAndParseJson(filename));
    // print('Number of JSON keys: ${jsonData.length}');
    final jsonData = await compute(_readAndParseJson, 'json_01.json');
    print('Number of JSON keys: ${jsonData}');
  }

  /// Reads the contents of the file with [filename],
  /// decodes the JSON, and returns the result.
  static Future<int> _readAndParseJson(String filename) async {
    final fileData = await rootBundle.loadString('assets/$filename');
    final jsonData = jsonDecode(fileData) as Map<String, String>;
    return jsonData.length;
  }
}

However, when I check the sample code on https://docs.flutter.dev/perf/isolates which also loads assets in isolate, it seems to have worked before. I will re-open this for further insights. The issue is reproduced in the latest Flutter master channel.

flutter doctor -v (stable and master)

[✓] Flutter (Channel stable, 3.19.4, on macOS 14.1 23B74 darwin-x64, locale en-VN)
    • Flutter version 3.19.4 on channel stable at /Users/huynq/Documents/GitHub/flutter
    • Upstream repository https://github.com/flutter/flutter.git
    • Framework revision 68bfaea224 (29 hours ago), 2024-03-20 15:36:31 -0700
    • Engine revision a5c24f538d
    • Dart version 3.3.2
    • 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 15.2)
    • Xcode at /Applications/Xcode.app/Contents/Developer
    • Build 15C500b
    • 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 1.87.2)
    • VS Code at /Applications/Visual Studio Code.app/Contents
    • Flutter extension version 3.84.0

[✓] 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 123.0.6312.58

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

• No issues found!

[!] Flutter (Channel master, 3.21.0-16.0.pre.14, on macOS 14.1 23B74 darwin-x64, locale en-VN)
    • Flutter version 3.21.0-16.0.pre.14 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 f5b65bad0f (2 hours ago), 2024-03-27 18:20:55 -0700
    • Engine revision c602abdbae
    • Dart version 3.4.0 (build 3.4.0-279.0.dev)
    • DevTools version 2.34.0-dev.12
    • 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 15.2)
    • Xcode at /Applications/Xcode.app/Contents/Developer
    • Build 15C500b
    • 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 1.87.2)
    • VS Code at /Applications/Visual Studio Code.app/Contents
    • Flutter extension version 3.84.0

[✓] 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 123.0.6312.86

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

! Doctor found issues in 1 category.

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Unhandled Exception: Binding has not yet been initialized - when running Isolate sample example about flutter HOT 4 CLOSED

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	class PlatformAssetBundle extends CachingAssetBundle {
	@override
	Future<ByteData> load(String key) {
	final Uint8List encoded = utf8.encode(Uri(path: Uri.encodeFull(key)).path);
	final Future<ByteData>? future = ServicesBinding.instance.defaultBinaryMessenger.send(
	'flutter/assets',

	/// Send a binary message to the platform plugins on the given channel.
	///
	/// Returns a [Future] which completes to the received response, undecoded,
	/// in binary form.
	Future<ByteData?>? send(String channel, ByteData? message);