Hello for all! Can anybody help with error "kotlin...

# multiplatform

[Andrey Makovskiy]

Hello for all! Can anybody help with error "kotlin.native.concurrent.InvalidMutabilityException: mutation attempt of frozen". Problem is that object is created in main thread on iOS and exception thrown from constructor. When and why object become frozen?

[Marc Knaup]

You can find more info here:
https://github.com/JetBrains/kotlin-native/blob/master/CONCURRENCY.md

What's your concrete code?

[Andrey Makovskiy]

I already read this article I don't wee why objects become frozen: it is not global variable and song object definition, it references to static object but as I understand it should not make it frozen. They are not objects but classes, instance is created in AppDelegate.application, code is very big, I can't show all. Initially that was framework developed as multiplatform, but tested only in Android.

[Andrey Makovskiy]

error trace show that it works in main thread from call AppDelegate.application()

[Arkadii Ivanov]

Could you please provide more info about what's your class is and how it's created. Some code would be nice.

[Jurriaan Mous]

You can use ensureNeverFrozen to see an exception thrown on what freezes the object. https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.native.concurrent/ensure-never-frozen.html

[Andrey Makovskiy]

OK, thanks 🙂 I'll try it

[Andrey Makovskiy]

mmm... this will not help

[Andrey Makovskiy]

function available only from native, when object which frozen is creating inside of common code

[Andrey Makovskiy]

@Arkadii Ivanov as I said there is a big amount of code. Too much to publish here and I sure it is not only one place where something will be frozen

[Andrey Makovskiy]

I need to understand mechanism and prevent it in all

[Jurriaan Mous]

You could make an expect/actual for the function? In the past I found some issues with freezing this way in my common code. I remember mostly being caused by code inside an object or by Lambdas being passed with an unneeded scope which was later frozen.

[Jurriaan Mous]

(Setting scope to Unit for some of those lambdas helped in latter case)

[Andrey Makovskiy]

Thanks. Already done that but it sill crash with "Mutation attempt of already frozen object MyClass" when MyClass have init { ensureNeverFrozen() }

[Andrey Makovskiy]

what if I want to provide a listener for another thread???

[Arkadii Ivanov]

What is "listener for another thread"? Please provide some piece of code.

[Marc Knaup]

Is MyClass a class or an object?
If it is a class then where is an instance of it created?

[Andrey Makovskiy]

MyClass is a class, instance is created in AppDelegate.application() method

[Marc Knaup]

And where is the instance stored?