Isolate Example

A sample application that demonstrate best practices when using isolates.

Goals

• Display the performance benefits of isolates when using them in the right situation.
• Show how to use the compute method for straightforward computations.
• Demonstrate how to initialize and use an isolate.
• Show the cost of moving data between isolates and provide alternatives.

The important bits

performance_page.dart

Compares running a large computation on the main isolate with running the same calculation on a second isolate. When the main isolate is used, Flutter is unable to render new frames, and the SmoothAnimationWidget's animation freezes.

infinite_process_page.dart

Creates an isolate used to run an infinite loop that sums batches of 100M randomly generated numbers at a time. Users can start, terminate, pause, and resume the isolate, as well as modify how the calculation is performed.

data_transfer_page.dart

Demonstrates how expensive it is to move large amounts of data between isolates and a better alternative to move data. This page creates an isolate that can add up a list of numbers and gives users three options for how to provide it with input:

• Send values normally using a List
• Send the values using TransferableTypedData
• Generate the values on the second isolate, so no copying is necessary

Users can then compare the performance of each approach using the displayed timestamps.

Questions/issues

If you have a general question about any of the techniques you see in the sample, the best places to go are:

• The FlutterDev Google Group
• The Flutter Gitter channel
• StackOverflow

If you run into an issue with the sample itself, please file an issue in the main Flutter repo.