Difference Between Isolates and Compute in Flutter

When developing mobile applications with Flutter, it’s important to consider performance and responsiveness to ensure a smooth user experience. Two tools that can be used to achieve this are Flutter Isolates and Flutter Compute. Both tools allow for parallel processing, but they have some differences that are worth exploring.

Flutter Isolates

Flutter Isolates provide a way to perform computationally expensive tasks in a separate thread or process, independent of the main thread. This is useful when performing tasks that might block the main thread, such as network requests, heavy calculations, or file I/O operations. By using isolates, these tasks can be performed in the background, without interfering with the user interface.

Isolates in Flutter are similar to threads in other programming languages. They have their own memory space and can run concurrently with other isolates. Communication between isolates is achieved through message passing, which involves sending and receiving messages using the isolate’s SendPort and ReceivePort APIs. Here’s an example of using isolates to perform a heavy computation:

Dart

void main() {
  final myIsolate = Isolate.spawn(computeFactorial, 5);
  myIsolate.then((isolate) => print('Factorial result: ${isolate.result}'));
}

void computeFactorial(int n) {
  int factorial(int n) => (n == 0) ? 1 : n * factorial(n - 1);
  final result = factorial(n);
  SendPort sendPort = IsolateNameServer.lookupPortByName('main');
  sendPort.send(result);
}

Don’t get worried by seeing this code it is just an example, here we spawn a new isolate and pass it the computeFactorial function and the value 5. The computeFactorial function computes the factorial of 5 and sends the result back to the main isolate using the SendPort API. Finally, we print the result in the main isolate.

Output:

Factorial result: 120

Flutter Compute

Flutter Compute is a simpler alternative to isolates that is designed for performing computationally expensive tasks on a separate thread within the same isolate. It is similar to the concept of a Future in Dart but with the added benefit of running the computation on a separate thread. Here’s an example of using Flutter Compute to perform a heavy computation:

Dart

Future<int> computeFactorial(int n) async {
  return await compute(_factorial, n);
}

int _factorial(int n) {
  return (n == 0) ? 1 : n * _factorial(n - 1);
}

void main() async {
  final result = await computeFactorial(5);
  print('Factorial result: $result');
}

In this example, we define the computeFactorial function, which calls the _factorial function using the compute API. The _factorial function computes the factorial of 5 recursively. Finally, we print the result in the main isolate.

Output:

Factorial result: 120

Both examples compute the factorial of 5, but the first example uses Flutter Isolates, while the second example uses Flutter Compute. The output is the same in both cases, but the implementation and underlying mechanisms differ.

Difference Table

Flutter Isolates	Flutter Compute
Provide a way to perform computationally expensive tasks in a separate thread or process.	Provides a simpler alternative to isolates for performing computationally expensive tasks.
Can be used for tasks that might block the main thread, such as network requests, heavy calculations, or file I/O operations.	Runs the computation on a separate thread within the same isolate.
Have their own memory space and can run concurrently with other isolates.	Similar to the concept of a Future in Dart, but with the added benefit of running the computation on a separate thread.
Communication between isolates is achieved through message passing.	Runs on the same memory space as the main thread.
Provide more flexibility and control, but may use more memory.	Suitable for simpler computations that don’t require coordination between different threads or processes.
Can communicate with other isolates using message passing.	Can only communicate with the main thread.

Conclusion

Overall, both Flutter Isolates and Flutter Compute can improve performance and responsiveness in a Flutter application, but they have different use cases and trade-offs. Choosing between them will depend on the specific requirements and constraints of your application.