ANRs after Compose BOM 2024.01.00 update

[argenkiwi]

I have been experiencing ANRs in my project after upgrading to Compose BOM 2024.01.00 and I am also observing these on 2024.02.00. I could not get anything meaningful from the logs, but I managed to narrow down the issue and it seems to be related to molecule AND my project.

When I move my presentation logic from the view to a view-model using molecule I start seeing ANRs:

class TestViewModel : ViewModel() {
    val stateFlow = viewModelScope.launchMolecule(RecompositionMode.Immediate) {
        var loading by remember { mutableStateOf(false) }
        LaunchedEffect(loading) {
            if (loading) {
                delay(2.seconds)
                loading = false
            }
        }

        loading to { loading = true }
    }
}

However, if I create an empty project and implement the same test in isolation I do not get an issue.

I got a report from Crashlytics this morning, here is a sample stacktrace:

main (blocked):tid=1 systid=16421 | waiting to lock <0x062953e1> (java.lang.Object) held by thread 39
       at androidx.compose.runtime.Recomposer$recompositionRunner$2$unregisterApplyObserver$1.invoke(Recomposer.kt:1565)
       at androidx.compose.runtime.Recomposer$recompositionRunner$2$unregisterApplyObserver$1.invoke(Recomposer.kt:976)
       at androidx.compose.runtime.snapshots.SnapshotKt.advanceGlobalSnapshot(Snapshot.kt:1815)
       at androidx.compose.runtime.snapshots.SnapshotKt.advanceGlobalSnapshot(Snapshot.kt:1830)
       at androidx.compose.runtime.snapshots.SnapshotKt.access$advanceGlobalSnapshot(Snapshot.kt:1)
       at androidx.compose.runtime.snapshots.Snapshot$Companion.sendApplyNotifications(Snapshot.kt:583)
       at app.cash.molecule.MoleculeKt$launchMolecule$3$1.invokeSuspend(molecule.kt:195)
       at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:33)
       at kotlinx.coroutines.internal.DispatchedContinuationKt.resumeCancellableWith(DispatchedContinuation.kt:367)
       at kotlinx.coroutines.intrinsics.CancellableKt.startCoroutineCancellable(Cancellable.kt:30)
       at kotlinx.coroutines.intrinsics.CancellableKt.startCoroutineCancellable$default(Cancellable.kt:25)
       at kotlinx.coroutines.CoroutineStart.invoke(CoroutineStart.kt:110)
       at kotlinx.coroutines.AbstractCoroutine.start(AbstractCoroutine.kt:126)
       at kotlinx.coroutines.BuildersKt__Builders_commonKt.launch(Builders.common.kt:56)
       at kotlinx.coroutines.BuildersKt.launch(unavailable:1)
       at kotlinx.coroutines.BuildersKt__Builders_commonKt.launch$default(Builders.common.kt:47)
       at kotlinx.coroutines.BuildersKt.launch$default(unavailable:1)
       at app.cash.molecule.MoleculeKt$launchMolecule$3.invoke(molecule.kt:193)
       at app.cash.molecule.MoleculeKt$launchMolecule$3.invoke(molecule.kt:190)
       at androidx.compose.runtime.snapshots.GlobalSnapshot$1$1$1.invoke(Snapshot.kt:1325)
       at androidx.compose.runtime.snapshots.GlobalSnapshot$1$1$1.invoke(Snapshot.kt:1324)
       at androidx.compose.runtime.snapshots.SnapshotKt.notifyWrite(Snapshot.kt:2142)
       at androidx.compose.runtime.SnapshotMutableStateImpl.setValue(SnapshotState.kt:316)
       at androidx.compose.animation.core.AnimationScope.setRunning$animation_core_release(AnimationState.kt:348)
       at androidx.compose.animation.core.SuspendAnimationKt.doAnimationFrame(SuspendAnimation.kt:358)
       at androidx.compose.animation.core.SuspendAnimationKt.doAnimationFrameWithScale(SuspendAnimation.kt:339)
       at androidx.compose.animation.core.SuspendAnimationKt.access$doAnimationFrameWithScale(SuspendAnimation.kt:1)
       at androidx.compose.animation.core.SuspendAnimationKt$animate$9.invoke(SuspendAnimation.kt:279)
       at androidx.compose.animation.core.SuspendAnimationKt$animate$9.invoke(SuspendAnimation.kt:278)
       at androidx.compose.animation.core.SuspendAnimationKt$callWithFrameNanos$2.invoke(SuspendAnimation.kt:304)
       at androidx.compose.animation.core.SuspendAnimationKt$callWithFrameNanos$2.invoke(SuspendAnimation.kt:303)
       at androidx.compose.runtime.BroadcastFrameClock$FrameAwaiter.resume(BroadcastFrameClock.kt:42)
       at androidx.compose.runtime.BroadcastFrameClock.sendFrame(BroadcastFrameClock.kt:71)
       at androidx.compose.runtime.Recomposer$runRecomposeAndApplyChanges$2$1.invoke(Recomposer.kt:558)
       at androidx.compose.runtime.Recomposer$runRecomposeAndApplyChanges$2$1.invoke(Recomposer.kt:551)
       at androidx.compose.ui.platform.AndroidUiFrameClock$withFrameNanos$2$callback$1.doFrame(AndroidUiFrameClock.android.kt:41)
       at androidx.compose.ui.platform.AndroidUiDispatcher.performFrameDispatch(AndroidUiDispatcher.android.kt:109)
       at androidx.compose.ui.platform.AndroidUiDispatcher.access$performFrameDispatch(AndroidUiDispatcher.android.kt:41)
       at androidx.compose.ui.platform.AndroidUiDispatcher$dispatchCallback$1.doFrame(AndroidUiDispatcher.android.kt:69)
       at android.view.Choreographer$CallbackRecord.run(Choreographer.java:1035)
       at android.view.Choreographer.doCallbacks(Choreographer.java:845)
       at android.view.Choreographer.doFrame(Choreographer.java:775)
       at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:1022)
       at android.os.Handler.handleCallback(Handler.java:938)
       at android.os.Handler.dispatchMessage(Handler.java:99)
       at android.os.Looper.loopOnce(Looper.java:201)
       at android.os.Looper.loop(Looper.java:288)
       at android.app.ActivityThread.main(ActivityThread.java:7842)
       at java.lang.reflect.Method.invoke(Native method)
       at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:548)
       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1003)

I am struggling to narrow the problem down far enough to even considering raising an issue, but I thought I would reach out in case anyone else is facing this or could maybe have a notion of what the problem could be.

[argenkiwi]

UPDATE: it seems updating viewModelScope.launchMolecule(RecompositionMode.Immediate) to viewModelScope.launchMolecule(RecompositionMode.ContextClock, AndroidUiDispatcher.Main). I have been using RecompositionMode.Immediate in my view-models without issues so far and it's beyond my understanding why this issue surfaced now. I would appreciate any insights whoever reads this could have. Happy to close the discussion otherwise.

[JakeWharton]

Yeah we'll take a look. It's possible we're using the Compose runtime APIs in a way that it doesn't expect which then broken with the Compose update.

[JakeWharton]

By the way this was also filed as an issue (#396) and is now filed upstream on Compose itself.