Error invoking produce inside a suspending method

[fabioCollini]

I am trying to use the channels and I am getting some strange behaviour. Everything works defining methods as CoroutineScope extension methods but there is a deadlock defining the same method as suspend and invoking coroutineScope at the beginning. In the channels guide all the methods are defined as CoroutineScope extension methods but it would be useful to define them as suspending. Here there is a test to reproduce it, testNormal and testExtension work correctly but testScope never finish:

class ExampleUnitTest {
    @Test
    fun testNormal() {
        runBlocking {
            launch(Dispatchers.IO) {
                val channel = produce {
                    send(1)
                    send(2)
                    send(3)
                }

                channel.consumeEach {
                    println(it)
                }
            }
        }
    }

    @Test
    fun testExtension() {
        runBlocking {
            launch(Dispatchers.IO) {
                val channel = produceExtension()

                channel.consumeEach {
                    println(it)
                }
            }
        }
    }

    @Test
    fun testScope() {
        runBlocking {
            launch(Dispatchers.IO) {
                val channel = produceCoroutineScope()

                channel.consumeEach {
                    println(it)
                }
            }
        }
    }

    private suspend fun produceCoroutineScope(): ReceiveChannel<Int> = coroutineScope {
        produce {
            send(1)
            send(2)
            send(3)
        }
    }

    private fun CoroutineScope.produceExtension(): ReceiveChannel<Int> = produce {
        send(1)
        send(2)
        send(3)
    }
}

I have just tryed to update to version 0.30.0-eap13, the problem remains using it.

[fvasco]

Hi @fabioCollini
in your testScope the produce factory have to complete before coroutineScope exits, so produceCoroutineScope cannot terminate.

You can use a different scope, like GlobalScope, or a channel capacity greater or equal to three (or CONFLATED, UNLIMITED).

I got a similar issue using the code GlobaScope.async { actor { ... channel.receive() ... } }, using this code there is no way to get the actor asynchronously, I have to use a GlobalScope explicitly (and this is the goal of CoroutineScope).

[elizarov]

@fvasco Thanks for the answer. I'm closing this one.