Help to understand behaviour in coroutine native-mt

[francismariano]

Hello guys.

I have the following object

object SharedFlowRepository {

    init {
        println("SharedFlowRepository - init")
    }

    private val _devices = MutableSharedFlow<Int>()
    val devices = _devices.asSharedFlow()

    suspend fun startScanLeDevice() {
        println("SharedFlowRepository - startScanLeDevice")
        withContext(Dispatchers.Default) {
            println("SharedFlowRepository - startScanLeDevice:launch")
            testeFlow().collect {
                println("SharedFlowRepository - startScanLeDevice:collect = $it")
                _devices.emit(it)
            }
        }
    }

    fun stopScanLeDevice() {
        println("SharedFlowRepository - stopScanLeDevice")
    }

    private fun testeFlow() = flow {
        for (i in 1..5) {
            delay(1000)
            println("presenter - testeFlow:emitting = $i")
            emit(i)
        }
    }
}

And the following class

class SharedFlowPresenter {

    private val mainScope = MainScope()
    private var scan: Job? = null

    init {
        println("SharedFlowPresenter - SharedFlowPresenter:init")
        ensureNeverFrozen()
        deviceScanDevice()
        stopScanLeDevice()      // LINE 1
    }

    private val repository = SharedFlowRepository

    private fun stopScanLeDevice() {
        repository.stopScanLeDevice()
    }

    private fun deviceScanDevice() {
        println("SharedFlowPresenter - deviceScanDevice")
        scan = mainScope.launch {
            println("SharedFlowPresenter - deviceScanDevice:launch")
            try {
                println("SharedFlowPresenter - deviceScanDevice:try")
                withTimeout(20000) {
                    println("SharedFlowPresenter - deviceScanDevice:withTimeout:withTimeout")
                    repository.devices.collect {
                        println("SharedFlowPresenter - deviceScanDevice:withTimeout:collect INT ====== $it")
                    }
                }
            } catch (e: TimeoutCancellationException) {
                println("SharedFlowPresenter - deviceScanDevice:catch : ${e.message}")
            }
        }.apply {
            invokeOnCompletion {
                println("SharedFlowPresenter - deviceScanDevice:invokeOnCompletation")
//                stopScanLeDevice()            // LINE 2
            }
        }
        mainScope.launch {
            println("SharedFlowPresenter - deviceScanDevice:startScanLeDevice")
            repository.startScanLeDevice()
        }
    }
}

Main function

fun main() {
    println("START")
    SharedFlowPresenter()
    CFRunLoopRun() // run event loop
}

The code above works fine but if I comment the LINE 1 and uncomment the LINE 2 I get kotlin.native.concurrent.FreezingException when calls repository.devices.collect . Can anyone help me to understand that?

Thank you so much

[qwwdfsad]

Sorry for being that late.

Please use #coroutines slack channel for general questions. Also, it is possible to use new MM #462 (comment) that has FreezingException gone