Hi, I'm using `collectAsState()` with a flow that ...

# compose

[Martin Nonnenmacher]

Hi, I'm using collectAsState() with a flow that emits new values very frequently, about 10 times a second. The problem is that the SnapshotStateObserver.applyMaps property keeps growing and consumes more and more memory over time. This can be reproduced with the code below. A heap dump shows that after 50,000 iterations there is a single instance of androidx.compose.runtime.snapshots.SnapshotStateObserver$ApplyMap[] that consumes about 100 MB. As it seems to be by design that applyMaps can only grow, is there a fundamental issue with my code, or is there another approach I could use for frequent updates without eventually running out of memory?

class TestState {
    private val scope = CoroutineScope(Dispatchers.Default)
    val value = MutableStateFlow(0)

    init {
        scope.launch {
            while (true) {
                value.value = value.value + 1
                delay(100)
            }
        }
    }
}

@Composable
fun App() {
    val state = remember { TestState() }
    val value = state.value.collectAsState()
    Text("value = ${value.value}")
}

[Zach Klippenstein (he/him) [MOD]]

I don't see anything there that should cause a memory leak aside from that scope never getting cancelled, but it sounds like we're leaking proportionally with time which that shouldn't do. Can you file a bug?

[olonho]

see https://issuetracker.google.com/issues/223222717

[Martin Nonnenmacher]

Just saw the response, @olonho thanks for creating the issue!