Merged threads on macOS and Windows

Flutter 3.35 merges the UI and platform threads by default on macOS and Windows.

Originally, Flutter had separate threads to produce UI frames and to interact with the native platform.

The split-thread design prevented Flutter apps and plugins from using Dart FFI to interoperate with native APIs that must be called on the platform thread.

Flutter 3.35 merges the UI and platform threads by default on macOS and Windows.

This mirrors iOS and Android, whose threads were merged by default in Flutter 3.29.

Merged threads should not affect your app.

If you suspect merged threads has regressed your app, please reach out on Issue 150525.

Landed in version: 3.33.0-0.0.pre
In stable release: 3.35

Relevant issue:

• Issue 150525

Relevant PRs:

• PR 166536
• PR 167472