IllegalStateException thrown when change a MutableState value in the background: "Reading a state that was created after the snapshot was taken or in a snapshot that has not yet been applied" [166486000]

Fixed

Bug

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Description

ma...@gmail.com

created issue #1

Aug 26, 2020 09:19PM

Version of Gradle Plugin: 4.2.0-alpha07
Version of Gradle: 6.6
Version of Java: 1.8
OS: Android 10

Compose options:

composeOptions {
    kotlinCompilerVersion "1.4.0"
    kotlinCompilerExtensionVersion "0.1.0-dev17"
}

Updating a MutableState value in the backgroung, sometimes I get the following error:

java.lang.IllegalStateException: Reading a state that was created after the snapshot was taken or in a snapshot that has not yet been applied
        at androidx.compose.runtime.snapshots.SnapshotKt.readError(Snapshot.kt:1495)
        at androidx.compose.runtime.snapshots.SnapshotKt.current(Snapshot.kt:1654)
        at androidx.compose.runtime.SnapshotMutableState.setValue(MutableState.kt:499)
        at com.manueldidonna.redhex.inventory.FakeInventory.fetchItems(Test.kt:26)
        at com.manueldidonna.redhex.inventory.TestKt$TestSnapshotCrash$2$1$1.invokeSuspend(Test.kt:60)

Code to reproduce is attached. See @Composable TestSnapshotCrash() It's a simple layout with 3 Tabs and a LazyColumn. Changing the tab, a new list is created in the background and assigned to a mutablestate. That state is used in the lazycolumn. If you change the tab very quickly and many times, the crash should happen.

TestSnapshotCrash.kt

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Comments

so...@google.com <so...@google.com> Aug 27, 2020 10:00AM

Assigned to ch...@google.com.

ch...@google.com <ch...@google.com> #2Aug 27, 2020 11:07PM

~~After upgrading to kotlin 2.1.0 and bumping remaining dependencies, things seem to work as expected again.~~ EDIT: My bad; was on the wrong branch. Those upgrades did NOT help.

ch...@google.com <ch...@google.com> #3Aug 28, 2020 12:53AM

I think I managed to track it down further:

In my Child composable, I'm actually hitting a TODO() statement:

@Composable
fun Child(isLoading: Boolean, items: List<MyDataClass>) {
    // ...
    if (notYetSupported) {
        TODO("This is not yet supported!")
    }
    // ...
}

It would seem that compose swallows this error and throws the above instead which is not very helpful.

ch...@google.com <ch...@google.com> Aug 28, 2020 05:58PM

Reassigned to ad...@google.com.

ap...@google.com <ap...@google.com> #4Aug 29, 2020 12:30AM

Marked as fixed.

The "pending composition has not been applied" error generally means that composition continued despite something in the hierarchy previously throwing an exception. Here it looks like something is continuing a subcomposition unexpectedly, possibly a LazyList.

We should see if we can improve this error messaging. Can you send over a more complete example? The snippets here aren't fleshed out enough to reproduce this swallowing behavior.

Issue 166486000