Dart: Concurrency | Isolates life cycle

Introduction: Dart's concurrency model, powered by isolates, offers a flexible and efficient way to handle concurrent tasks in your applications. In this blog post, we'll explore the life cycle of isolates in Dart, understanding how they are created, execute tasks, and eventually terminate. Buckle up as we embark on a journey through the intriguing world of isolate lifecycle management.

The Birth of an Isolate: Every Dart application starts with a main isolate, which represents the main execution thread. From there, developers have the power to create additional isolates for parallel execution. Isolates are spawned using the Isolate.spawn function, and each isolate operates independently, with its own memory space.

Example: Spawning an Isolate

import 'dart:isolate';

void main() async {
  print('Main isolate starts');

  // Spawning a new isolate
  Isolate.spawn(isolateFunction, 'Hello from the spawned isolate');

  // Performing tasks in the main isolate
  for (int i = 1; i <= 3; i++) {
    print('Main isolate task $i');
    await Future.delayed(Duration(seconds: 1));
  }
}

void isolateFunction(String message) {
  print('Spawned isolate received: $message');

  // Performing tasks in the spawned isolate
  for (int i = 1; i <= 3; i++) {
    print('Spawned isolate task $i');
    sleep(Duration(seconds: 1));
  }

  print('Spawned isolate ends');
}

Understanding Isolate Lifecycle:

1. Creation: Isolates are created using the Isolate.spawn function, which takes the entry-point function and an optional message that is passed to the spawned isolate.

2. Execution: Once created, isolates independently execute their assigned tasks. The main isolate and spawned isolates operate concurrently.

3. Communication: Isolates can communicate with each other by passing messages. In the example, the spawned isolate receives a message from the main isolate.

4. Termination: Isolates can terminate naturally when their tasks are complete. Alternatively, you can terminate an isolate programmatically using the Isolate.kill function.

Example: Terminating an Isolate

import 'dart:isolate';

void main() async {
  print('Main isolate starts');

  // Spawning a new isolate
  Isolate spawnedIsolate = await Isolate.spawn(isolateFunction, 'Hello from the spawned isolate');

  // Performing tasks in the main isolate
  for (int i = 1; i <= 3; i++) {
    print('Main isolate task $i');
    await Future.delayed(Duration(seconds: 1));
  }

  // Terminating the spawned isolate
  spawnedIsolate.kill(priority: Isolate.immediate);
}

void isolateFunction(String message) {
  print('Spawned isolate received: $message');

  // Performing tasks in the spawned isolate
  for (int i = 1; i <= 3; i++) {
    print('Spawned isolate task $i');
    sleep(Duration(seconds: 1));
  }

  print('Spawned isolate ends');
}