java.lang.IllegalStateException: Reading a state that was created after the snapshot was taken or in a snapshot that has not yet been applied

[sabotrev]

We are seeing a growing crash after upgrading from 0.11.2 to 0.14.0. Unfortunately, the stack trace does not include any of my app's code, and we haven't been able to figure out how to reproduce the issue.

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:2059)
    at androidx.compose.runtime.snapshots.SnapshotKt.current(Snapshot.kt:2402)
    at androidx.compose.runtime.DerivedSnapshotState.current(DerivedState.kt:167)
    at androidx.compose.runtime.DerivedSnapshotState$ResultRecord.readableHash(DerivedState.kt:142)
    at androidx.compose.runtime.DerivedSnapshotState$ResultRecord.isValid(DerivedState.kt:114)
    at androidx.compose.runtime.DerivedSnapshotState.currentRecord(DerivedState.kt:175)
    at androidx.compose.runtime.DerivedSnapshotState.getValue(DerivedState.kt:272)
    at me.saket.telephoto.subsamplingimage.RealSubSamplingImageState.getViewportTiles(RealSubSamplingImageState.kt:182)
    at me.saket.telephoto.subsamplingimage.RealSubSamplingImageState.access$getViewportTiles(RealSubSamplingImageState.kt:40)
    at me.saket.telephoto.subsamplingimage.RealSubSamplingImageState$LoadImageTilesEffect$2.invokeSuspend(RealSubSamplingImageState.kt:157)
    at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:33)
    at kotlinx.coroutines.DispatchedTask.run(DispatchedTask.kt:104)
    at androidx.compose.ui.platform.AndroidUiDispatcher.performTrampolineDispatch(AndroidUiDispatcher.android.kt:81)
    at androidx.compose.ui.platform.AndroidUiDispatcher.access$setScheduledFrameDispatch$p(AndroidUiDispatcher.android.kt:41)
    at androidx.compose.ui.platform.AndroidUiDispatcher.access$performTrampolineDispatch(AndroidUiDispatcher.android.kt:41)
    at androidx.compose.ui.platform.AndroidUiDispatcher$dispatchCallback$1.run(AndroidUiDispatcher.android.kt:57)
    at android.os.Handler.handleCallback(Handler.java:938)
    at android.os.Handler.dispatchMessage(Handler.java:99)
    at android.os.Looper.loop(Looper.java:233)
    at android.app.ActivityThread.main(ActivityThread.java:8063)
    at java.lang.reflect.Method.invoke(Method.java)
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:631)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:978)

I'll update here if I discover anything further, thanks!

[saket]

Oh boy, this is going to be challenging to investigate. I wonder if this is happening because the value of viewportTiles is backed by a state, and the values read on line 155 and 157 can differ in race conditions.

telephoto/zoomable-image/sub-sampling-image/src/androidMain/kotlin/me/saket/telephoto/subsamplingimage/RealSubSamplingImageState.kt

Lines 163 to 167 in 8a14941

	LaunchedEffect(imageCache, viewportTiles) {
	imageCache.loadOrUnloadForTiles(
	regions = viewportTiles.fastMapNotNull { if (it.isVisible) it.region else null }
	)
	}

I could change this to the following in an attempt to fix this:

val viewportTiles = this.viewportTiles
LaunchedEffect(imageCache, viewportTiles) {
  imageCache.loadOrUnloadForTiles(
    regions = viewportTiles.fastMapNotNull { if (it.isVisible) it.region else null }
  )
}

Thoughts? cc @rharter who I remember was investigating a similar crash last month and might have suggestions.

[SzyQ]

I think the reason it worked on version 0.11.2 was the RealSubSamplingImageState had simple states, which were assigned after the calculation was ready.
Version 0.14.0 is using derivedStateOf more extensively, which I think are a bit buggy and hard to debug once they cause a crash. Most recently there was a fix for a nested derivedStateOf, where the changes correlate with the stacktrace we saw in the crashes here.
So once this fix is published, we will be ready to verify if it fixes the problem.