[Flutter] Hot release doesn't free up the RAM taken by the model

[esuljic]

In the development, I start the Isolate.spawn with a kokoro-en-v0_19 model. After hot restarting the app, it doesn't free the memory used in the previous VM instance. It is reproducable in both Android and iOS for me. I am attaching memory charts of both platforms, and you can see the hot restart event clearly there. For every hot restart it increases by 800-900MBs, until crashed.

[csukuangfj]

@dosu

[dosubot[bot]]

This looks like a native memory leak: Flutter hot restart resets the Dart VM but doesn't guarantee cleanup of native resources, especially those allocated by isolates or native libraries like sherpa-onnx. If the model or native resources aren't explicitly disposed before a hot restart, their memory can persist and accumulate with each restart.

Check if the plugin or your code provides a way to dispose or unload the model and native resources before a hot restart. Make sure isolates are properly terminated and any native cleanup methods are called. If no explicit disposal is available, this may be a limitation of the current integration between Flutter and the native library. Testing with a minimal example can help confirm if the leak is specific to sherpa-onnx or a general native resource management issue in Flutter.

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