I have a question. I'm not sure if this is for som...

# compose

[Mantas Varnagiris]

I have a question. I'm not sure if this is for some reason intended or a bug. In Activity if I do this

setContent {
    onActive {
        Log.d("ASD", "onActive")
    }
    onDispose {
        Log.d("ASD", "onDispose")
    }
}

1. Start app - onActive is called
2. Press back to leave app - onDispose NOT called
3. Open app again - onActive is called
So if we depend on onDispose to cleanup resources and it's not called - leaks happen

[shikasd]

Noticed the same issue with @Model class.
When subscribing to a static model, onDispose is not called and onActive is called twice after restarting activity (with don't keep activities).

[Mantas Varnagiris]

Yes so if you use those leaked resources they get duplicated every time you restart the app

[mbonnin]

@Mantas Varnagiris it might be this issue: https://kotlinlang.slack.com/archives/CJLTWPH7S/p1582580819055700?thread_ts=1582474949.025300&cid=CJLTWPH7S

[mbonnin]

Doe sit work if you do setContent {} in onDestroy ?

[Mantas Varnagiris]

Ah yes this this seems related. Good catch.

[Mantas Varnagiris]

OK so seems like the workaround for now is to store a reference to Composition returned by setContent {} and then call Composition.dispose() inside onDestroy in Activity

[Mantas Varnagiris]

Thanks @mbonnin for pointing this out!

[codeslubber]

Was just thinking yesterday that like politics, programming tends to solve some problems, and others just keep reappearing. The C++ community lost their mind over destructors, and of course when Java came along, it was impossible to do anything on destruction because it might not happen until the memory was collected…

[Leland Richardson [G]]

to clarify though, onDispose is not a GC-triggered lifecycle in any way. it’s a compose-specific lifecycle.

The code snippet above not working as expected is a bug, not a misunderstanding. Sorry about that ;)