Determine recomposition trigger [332234107]

Assigned

Feature Request

Status Update

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Description

mg...@gmail.com

created issue #1

Apr 1, 2024 02:58PM

As an application becomes more complex, the difficulty of determing what is causing a recomposition increases. No amount of skill or experience can allow you to quickly identify what triggered the recomposition, it is just a major chore.

In the best case, it would be super useful if we could do something like this:

@Composable
fun Component() {
    println(recompositionCause())
}

recompositionCause here is a debugging statement, not to be used in production code. Its performance does not matter at all.

I expect it to print something like:

parameter `width` of `SomeComponent` changed

Is this at all possible?

From googling, I see that Android Studio has some tools built into the IDE that help with identifying recomposition triggers. However, I'm looking for something that works on multplatform (desktop, in particular) and that doesn't require the IDE at all. I use IntelliJ, not Android studio. But in any case, an IDE feature wouldn't really fit my needs and shouldn't be neccesarry.

Also DebugProbes from kotlinx.coroutines comes to mind. I am essentially looking for something similar to this.

With coroutines debug probles, we have to call install to start recording. It would be totally fine if we also had to install some probe at the start of our application in order for this to work.

Originally posted in a Compose Multiplatform discusssion. The Jetbrains team said that this issue would be better addressed by Google since Google is working on the Compose runtime, so I copied the post here.

Comments

mg...@gmail.com <mg...@gmail.com> #2Apr 1, 2024 02:59PM

Also doesn't work in AS 2024.3.2 Canary 4 and Compose 1.8.0-beta01

mg...@gmail.com <mg...@gmail.com> #3Apr 1, 2024 03:01PM

Andrei: Is this the same as b/388030459?

Message last modified on Apr 1, 2024 03:01PM

mn...@google.com <mn...@google.com> Apr 1, 2024 04:18PM

Assigned to je...@google.com.

al...@google.com <al...@google.com> #4Apr 4, 2024 04:18PM

Triage notes: Needs investigation. Assigning for later.

al...@google.com <al...@google.com> #5Feb 20, 2025 07:21PM

Could you share the AppScaffoldTopBar function that fails here? This seems different from b/388030459 since it fails with expression that is not captured.

al...@google.com <al...@google.com> #6Feb 20, 2025 07:24PM

Reconstructed from IR:

@Composable
fun AppScaffoldTopBar(
    showBackArrow: Boolean,
    showSearch: Boolean,
    title: String?,
    onBackClick: () -> Unit,
    modifier: Modifier = Modifier,
    actions: ImmutableList<AppScaffoldNavigationAction>
) {
    if (!showSearch) {
        TitledTopAppBar(
            title = title,
            showBackArrow = showBackArrow,
            modifier = modifier,
            actions = actions,
            onBackClick = onBackClick
        )
    } else {
        TopAppBar(
            title = {
                // Composable lambda for title
                AppScaffoldTopBarTitle(showBackArrow)
            },
            modifier = modifier,
            navigationIcon = {
                // Composable lambda for navigation icon
                AppScaffoldTopBarNavigationIcon(showBackArrow, onBackClick)
            },
            actions = {
                // Composable lambda for actions
                AppScaffoldTopBarActions(actions)
            }
        )
    }
}

This seems /extremely/ weird to me, because showSearch is just a regular parameter that is used in function body only once. We need more context about surrounding code to figure out why it crashed the compiler.

Issue 332234107