Hi <@UHAJKUSTU> when i do `navigation.pop()` it...

# decompose

[Shivam Kanodia]

Hi @Arkadii Ivanov when i do navigation.pop() it seems that the popped component is not released from memory as on popping the memory usage is not freed up, rather if i keep pushing and popping alternately memory usage keeps increasing in ios app.

[Arkadii Ivanov]

I'm not sure, but on Kotlin/Native the GC may be running later when needed. Could this be the case? Maybe try triggering GC explicitly and check if the memory goes down?

[Arkadii Ivanov]

Also worth checking the UI, maybe there are some kind of cycling references.

[Shivam Kanodia]

Memory is not released till minutes after popping

[Arkadii Ivanov]

If the memory is released eventually, then this is the K/N behaviour.

[Arkadii Ivanov]

You can try manually without Decompose. Try allocating an array (like 1Kb) and remember to a variable, then assign null.

[Shivam Kanodia]

Ok will check and share more insights

[Arkadii Ivanov]

There is some information in the docs: https://kotlinlang.org/docs/native-memory-manager.html

[Arkadii Ivanov]

E.g. it says that memory collection is executed periodically.

[Shivam Kanodia]

Check this recording of memory usages @Arkadii Ivanov

Screen Recording 2023-07-21 at 4.44.08 PM.mov

[Arkadii Ivanov]

What if instead of navigation, you will do the following in Kotlin on every button click:

fun foo() {
val x= ByteArray(1000000)
pintln(x.size)
}

[Shivam Kanodia]

ok

[Shivam Kanodia]

private fun onProjectListingOutput(output: ProjectListingComponent.Output): Unit =
        when (output) {
            is ProjectListingComponent.Output.NavigateBack -> navigation.pop()
            is ProjectListingComponent.Output.NavigateToProjectDetails -> {
                navigation.push(Configuration.ProjectDetails(projectId = output.projectId))
            }

            is ProjectListingComponent.Output.Logout -> {
                navigation.replaceAll(Configuration.EnterMobileNumber)
            }

            is ProjectListingComponent.Output.NavigateToNotification -> {
                foo()
//                navigation.push(Configuration.Notification)
            }
        }

    fun foo() {
        val x = ByteArray(1000000)
        println(x.size)
    }

[Shivam Kanodia]

done

[Shivam Kanodia]

each time i click 1MB memory usage increases

[Arkadii Ivanov]

On the video, I can see that the memory goes a bit up when you return back to the My Projects screen. When you push Notifications, it goes a bit down, and then again up when you pop to My Projects. This doesn't look like a memory leak. Worth checking what actually uses consumes the memory in My Projects screen

[Shivam Kanodia]

like it went from 165 to 170Mb then didnt increases

[Arkadii Ivanov]

Well, the video doesn't indicate any memory leaks. It could be your memory cache consuming the memory (if any), repositories, etc. Also make sure you don't accumulate any data every time My Project screen resumes.

On my side, I will check the Decompose sample on iOS.

[Shivam Kanodia]

check at 2:05 minutes of video, even when i click on notification and go to detail screen and then come back to notification memory usga ejumps up again , indicating that there is no issue in My Projects screen as it is the same case with Notification screen @Arkadii Ivanov

[Arkadii Ivanov]

At 2:05 you are going deeper to a notification item screen. Then when you go back to notifications, the screen clearly does something, and the memory increases. That's my observation.

[Arkadii Ivanov]

I will provide a way how you could check whether a class is deallocated or not, a bit later.

[Shivam Kanodia]

yes, please. THanks

[Arkadii Ivanov]

Re: deallocation checker

In commonMain:

internal expect fun Any.nativeDeallocChecker(): Any

In iosMain:

import kotlin.native.internal.createCleaner

@OptIn(ExperimentalStdlibApi::class)
internal actual fun Any.nativeDeallocChecker(): Any {
    println("Allocated: $this")

    return createCleaner(argument = this) { println("Deallocated: $it") }
}

Then inside a component class:

class DefaultSomeComponent : SomeComponent {
    private val marker = listOf("Counter")
    private val deallocChecker = marker.nativeDeallocChecker()

    // The reset of the code
}

It is important that the checker must not reference the component itself, it should only reference the marker, otherwise it may not work. Once the component is deallocated, the marker object is also deallocated and the checker will print the message.

I have just checked on the Decompose sample, all DefaultCounterComponent instances are deallocated eventually after pop. Not immediately, but eventually after some time. In my case it is ~10 seconds.

[Shivam Kanodia]

@Arkadii Ivanov Thanks, will test tomorrow and share the the insights. Thanks