Multithreading e pool de threads trabalhadores para Dart / Flutter, para deslocar tarefas intensivas em CPU e I/O pesadas para Isolates ou threads Web Worker (JS+WASM).
^1.1.0^2.1.0^1.1.0^1.11.0^1.0.0^1.1.1^2.11.1^4.4.14^1.15.0>=4.0.0 <7.0.0^1.30.0^1.9.1^3.1.3Texto original em inglês. Visite o GitHub para a versão atual.
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Squadron - Multithreading and worker pools in DartOffload CPU-bound and long running tasks and give your apps some air! Quick Start • Why Squadron? • Wiki Documentation • Samples Pub Package Dart Platforms Flutter Platforms Pub Points Likes Downloads License Null Safety Dart Style |
Dart is single-threaded by nature. While Isolate.run() is great for one-off tasks, it creates overhead for frequent operations, and is not available on browser platforms.
Squadron provides:
Stream return types from workers.sequenceDiagram
autonumber
participant App as Main App (UI)
box rgb(40, 100, 200, 0.1) Squadron / Generated Code
participant Pool as HelloWorldWorkerPool/Worker
end
box rgb(0, 150, 0, 0.1) Background Thread
participant Service as User Service
end
App->>Pool: worker.hello('Squadron')
Pool->>Service: Assign Task (Marshaled)
activate Service
Note over Service: Executing on background Isolate/Web Worker
Service-->>Pool: Return Result (Unmarshaled)
deactivate Service
Pool-->>App: Future<String> Result
Add Squadron to your dependencies and squadron_builder to your dev dependencies:
dependencies:
squadron: ^7.4.0
dev_dependencies:
build_runner:
squadron_builder: ^9.0.0
Run dart pub get to install.
Create a class with the logic you want to run in the background. Use @SquadronService and @SquadronMethod annotations.
// file: hello_world.dart
import 'dart:async';
import 'package:squadron/squadron.dart';
import 'hello_world.activator.g.dart';
part 'hello_world.worker.g.dart';
@SquadronService(baseUrl: '~/workers', targetPlatform: TargetPlatform.all)
base class HelloWorld {
@SquadronMethod()
FutureOr<String> hello([String? name]) {
name = name?.trim() ?? 'World';
return 'Hello, $name!';
}
}
Squadron uses code generation to handle the boilerplate of thread communication. Run the following command:
dart run build_runner build
This creates HelloWorldWorker and HelloWorldWorkerPool. These classes implement the same interface as your service but proxy calls to background threads.
In your application, instantiate the worker and use it like a normal service.
[!IMPORTANT]
Always stop your workers. Failure to callworker.stop()will keep your program running indefinitely.
import 'hello_world.dart';
void main() async {
final worker = HelloWorldWorker();
try {
// Squadron starts the worker automatically on the first call
final message = await worker.hello('Squadron');
print(message);
} finally {
worker.stop(); // Clean up the background thread
}
}
Squadron is designed for a "write once, run anywhere" experience. When targeting the web, you must compile your worker entry points:
# Compile to JavaScript
dart compile js ".\src\lib\hello_world.web.g.dart" -o "..\web\workers\hello_world.web.g.dart.js"
# Compile to Web Assembly
dart compile wasm ".\src\lib\hello_world.web.g.dart" -o "..\web\workers\hello_world.web.g.dart.wasm"
Squadron will automatically detect the runtime environment and choose the correct implementation.
Because workers run in separate memory spaces, data must be serialized ("marshaled") to cross thread boundaries. While base types (Strings, Numbers, Lists, Maps) are handled automatically, custom objects require a SquadronMarshaler.
📖 Learn more: Data Transfer and Types & Marshaling Wiki
Exceptions thrown in a worker are caught, serialized, and re-thrown on the caller's side, preserving the stack trace and error information where possible.
📖 Learn more: Exception Management Wiki
Debugging background workers can be tricky. Squadron provides mechanisms to forward log messages from workers back to the main thread's debugger or console.
📖 Learn more: Observability and Logging Wiki