Release build much slower than debug build when running on isolates with Command.executeThread() on Android

[eduribas]

The following simple code runs much slower in release build than in debug build on Android:

import 'package:flutter/material.dart';
import 'package:image_picker/image_picker.dart';
import 'package:image/image.dart' as im;

void main() {
  runApp(const MainApp());
}

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

  @override
  State<MainApp> createState() => _MainAppState();
}

class _MainAppState extends State<MainApp> {
  Duration? _elapsedTime;
  bool _running = false;

  void _processPicture() async {
    final file = await ImagePicker().pickImage(source: ImageSource.gallery);
    if (file != null) {
      setState(() {
        _running = true;
      });
      final bytes = await file.readAsBytes();
      final command = im.Command()
        ..decodeImage(bytes)
        ..encodeJpg();
      final startTime = DateTime.now();
      await command.executeThread();
      setState(() {
        _running = false;
        _elapsedTime = DateTime.now().difference(startTime);
      });
    }
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: Center(
          child: Column(
            mainAxisAlignment: MainAxisAlignment.spaceAround,
            children: [
              if (_running)
                const CircularProgressIndicator()
              else
                Text(_elapsedTime != null
                    ? 'Elapsed milliseconds: ${_elapsedTime!.inMilliseconds}'
                    : ''),
              OutlinedButton(
                onPressed: _processPicture,
                child: const Text('Select picture'),
              ),
            ],
          ),
        ),
      ),
    );
  }
}

[eduribas]

By further testing I noticed that even if not running in isolates, by changing await command.executeThread(); to await command.execute(); in the code above, it still runs around 25% slower in release builds than in debug builds, in a Pixel 7 Pro.

[brendan-duncan]

This kinda feels like a Dart issue, I'm not sure what I'd be able to do about it. It must be hitting some performance penalty case for Dart release optimizations. I agree it's a terrible performance loss, and completely backwards to what you would expect.

[eduribas]

This kinda feels like a Dart issue, I'm not sure what I'd be able to do about it. It must be hitting some performance penalty case for Dart release optimizations. I agree it's a terrible performance loss, and completely backwards to what you would expect.

Do you think it is related to this flutter issue: https://github.com/flutter/flutter/issues/140351 ?

As discussed in that issue, the usage of num in computations is really problematic for the AOT compiler used for release builds.

[brendan-duncan]

I can take a look at num usage when I get a chance.

[brendan-duncan]

I suspect there is is something similar going on, but I don't know if it's num causing the performance hit with the AOT release build. num isn't used in the decoders and encoders.