Dart: Unexpected Behavior When Using Isolate with Synchronous Code and Shared Data
I'm maintaining legacy code that I'm stuck trying to I'm stuck trying to I'm working on a project and hit a roadblock....... After trying multiple solutions online, I still can't figure this out. Quick question that's been bugging me - I'm trying to implement isolates in my Dart application to handle some heavy computations without blocking the main thread... However, I'm encountering unexpected behavior when accessing shared data. I created an isolate to perform calculations, but when I pass an object to the isolate, modifications made in the isolate do not reflect in the main isolate, leading to stale data. Here's a simplified version of my code: ```dart import 'dart:async'; import 'dart:isolate'; class SharedData { int value; SharedData(this.value); } void computeInIsolate(SendPort sendPort) { final receivePort = ReceivePort(); sendPort.send(receivePort.sendPort); receivePort.listen((message) { if (message is SharedData) { message.value += 10; // Trying to modify the shared data sendPort.send(message); } }); } Future<void> main() async { final receivePort = ReceivePort(); await Isolate.spawn(computeInIsolate, receivePort.sendPort); final sendPort = await receivePort.first; final sharedData = SharedData(5); sendPort.send(sharedData); final result = await receivePort.first; print('Result: ${result.value}'); // Expecting 15 } ``` When I run this code, I expect it to print `Result: 15`, but I get `Result: 5`. I thought that passing `SharedData` would allow me to modify it within the isolate, but it seems that Dart's isolates work with message passing, and the object is not shared between them. I tried using `SendPort` and `ReceivePort` for communication, but it didn’t solve the issue. What is the correct way to handle shared data across isolates, or is there a better approach for this scenario? I'm using Dart SDK version 2.15. I'd really appreciate any guidance on this. This is part of a larger CLI tool I'm building. What am I doing wrong? I'd love to hear your thoughts on this. Any pointers in the right direction? I'm using Dart 3.9 in this project. I'd be grateful for any help. This is for a application running on Linux.