Fixed
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Comments
se...@google.com
dh...@gmail.com
Yigit, do you have time to fix it?
reemission of the same liveData is racy
reemission of the same liveData is racy
ap...@google.com
Thanks for the detailed analysis. This may not be an issue anymore since we've started using Main.immediate there but I' not sure; I'll try to create a test case.
dh...@gmail.com
just emitting same live data reproduces the issue.
@Test
fun raceTest() {
val subLiveData = MutableLiveData(1)
val subject = liveData(testScope.coroutineContext) {
emitSource(subLiveData)
emitSource(subLiveData) //crashes
}
subject.addObserver().apply {
testScope.advanceUntilIdle()
}
}
@Test
fun raceTest() {
val subLiveData = MutableLiveData(1)
val subject = liveData(testScope.coroutineContext) {
emitSource(subLiveData)
emitSource(subLiveData) //crashes
}
subject.addObserver().apply {
testScope.advanceUntilIdle()
}
}
il...@google.com
With 2.2.0-alpha04 (that use Main.immediate), the issue seems to be still there (I tested it by calling emitSource() twice, like your test case)
Description
Devices/Android versions reproduced on: robolectric, emulator, real devices
I have an activity, and a fragment in it (MasterFragment).
Than I add nested fragment (NestedFragmentWithViewModel) to a MasterFragment.
NestedFragmentWithViewModel obtains viewmodel by `ViewModelProviders.of(this)`
Than I replace it (with adding to a backstack) with another fragment (NestedFragment).
After that, activity gets recreated, which is causing:
- MasterFragment to recrete
- NestedFragment (as it is on top of backstack) to recreate
After that, activity gets destroyed, which is causing:
- MasterFragment to destroy and clear its ViewModelStore
- NestedFragment to destroy and clear its ViewModelStore
But no one cares neither about NestedFragmentWithViewModel in the backstack, nor about clearing its ViewModelStore.
It is not cleared when fragment is added to a backstack (cause backstack can be popped to show fragment again).
And it is not cleared when MasterFragment destroys, cause it calls onDestroy on all its 'created' nested fragments, but fragments in a backstack were not created after activity get recreated, so should not be destroyed.
Fragment's ViewModelStore is cleared in fragment's onDestroy() in case activity.isFinishing(). That never happens so, whole ViewModelStore gets leaked.
It is not a totally FragmentManager issue, cause its respects lifecycle of fragments - 'what is dead may never die'.
So it seems fragment's logic to clear its ViewModelStore should be fixed.
Project with described scenario is attached.