Questions: processes, memory leaks, signing releases

[pushkinman]

Hello @IVLIVS-III, I wanted to ask a couple of questions about the solution and I would be greatful for your responce:

1. In what process does the python code run? Is Python runtime hosted within Flutter or some other process?
2. Are there any risks of memory leaks? Does the process of releasing memory is properly taken care of or there are certain practices that much be followed?

Are there any potential memory leaks in the following code from your examples?

void primitivesSqrt() {
    final PrimitivesModule primitivesModule = PrimitivesModule.import();
    final int sqrt = primitivesModule.sqrt(9);
    debugPrint("Sqrt: $sqrt");
  }

3. Could there be a problem bundling Python-FFI in release configurations? I.e. do you know of any potential problems with signing macOS app bundle?

[IVLIVS-III]

1. In what process does the python code run? Is Python runtime hosted within Flutter or some other process?

As any other dynamic library that is loaded via dart:ffi, I believe that the Python code runs inside the Flutter process.

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2. Are there any risks of memory leaks? Does the process of releasing memory is properly taken care of or there are certain practices that much be followed?

At this point in time, the project does not try to correctly follow CPython reference counting. Since reference counting is extremely difficult to do correctly, I prioritized implementing features over ensuring a correct and minimal refcount. Instead the refcount is always at least as high as necessary, but might be higher than what the correct refcount would be. This has two effects:

• any Python object that the Dart code wants to interact with is available in memory, but
• any Python object that the Dart code interacted with, might not be garbage collected, even if it is no longer in use.

However, when stopping the Flutter process, the operating system automatically reclaims all memory including any Python object that was not in use but also not garbage collected.

Are there any potential memory leaks in the following code from your examples?

After importing the Python module, as well as accessing the sqrt function, both Python objects (the module and the function) would remain in memory for as long as the flutter app is running.

Note: Sometimes, the refcount is handled correctly. E.g. arguments to Python functions are released after the function has been called. In the provided example, the 9 would have been released.

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3. Could there be a problem bundling Python-FFI in release configurations? I.e. do you know of any potential problems with signing macOS app bundle?

No, the dynamic Python library used on macOS is signed with a valid Apple Developer Distribution Certificate, thus neither the plugin consumer (developer that uses dart_python_ffi) nor the end user (user of an app which contains dart_python_ffi) has to worry about anything. The macOS operating system will automatically and successfully validate the bundled dynamic Python library.