[StackNavigation] InstanceKeeper instances of component are destroyed earlier than component itself, leading to access to released resources.

[HeroBrine1st]

Hello. I found that in StackNavigation Instances of component are destroyed first, and then lifecycle of component is going pause-stop-destroy. I found that when implemented pause of video play on pause of component (which IMO is good as video is not playing in background) and also "releasing" (i.e. destroying with release of resources like threads etc) ExoPlayer in onDestroy method of Instance.

So, when I navigate back from screen with video I see this warning in logs:

Handler (android.os.Handler) {c3b8656} sending message to a Handler on a dead thread
java.lang.IllegalStateException: Handler (android.os.Handler) {c3b8656} sending message to a Handler on a dead thread

That is a clear signal that Instance::onDestroy is called first, and then Lifecycle.Callbacks::onPause is called (because stack trace leads to onPause).

I also found the source of this exception in Decompose code. Lines 189 and 190 are in wrong order and that is the problem. I think reproductions steps are not needed as the error is clear from code below:

Decompose/decompose/src/commonMain/kotlin/com/arkivanov/decompose/router/children/ChildrenNavigator.kt

Lines 181 to 193 in 3fbf7c8

	private fun destroyOldItems(
	newConfigurations: Set<C>,
	oldItems: Collection<ChildItem<C, T>>,
	) {
	for (item in oldItems) {
	val child = item as? Created ?: continue
	if (item.configuration !in newConfigurations) {
	child.backHandler.stop()
	child.instanceKeeperDispatcher.destroy()
	child.lifecycleRegistry.destroy()
	}
	}
	}

Why this should not happen: because instances of classes should be destroyed only when there are no external links to them, i.e. noone can access already destroyed classes or releases resources. On android, ViewModel is destroyed later than Activity, for example.

Btw, I use 2.0.0-alpha-01 version, and tried with 2.0.0-alpha-02 - the error is still here. Artifacts used: decompose and extensions-compose-jetpack on Android 13 (Pixel Experience).

[arkivanov]

Hello and thanks for reporting! Indeed it looks like a bug. I will investigate it further and provide updates here.

[arkivanov]

Thanks again for reporting, will be fixed in the next release.