Hi all, Is there a Kotlin coroutine implementation...

# coroutines

[suppoze]

Hi all,
Is there a Kotlin coroutine implementation equivalent to

private val queue = Executors.newSingleThreadExecutor()
//...
    fun submit(data: Data) {
        queue.submit { updateData(data) }
    }

? I was thinking about

private val queue = Executors.newSingleThreadExecutor().asCoroutineDispatcher()
// ...
    fun submit(data: Data) = runBlocking {
        launch(queue) {
            updateData(data)
        }
    }

but it's seems to be running sequentially somehow? Am I doing something wrong?

[marstran]

The coroutineScope that is created by runBlocking waits for the launch to complete.

[marstran]

If you don't have any other scope to run it on, you could do GlobalScope.launch { updateData(data) }.

[suppoze]

Yes, that's what I observed, however I don't understand why should it wait for launch to complete. E.g. in this example https://github.com/Kotlin/kotlinx.coroutines/blob/master/docs/coroutine-context-and-dispatchers.md#unconfined-vs-confined-dispatcher
runBlocking is used in conjuction launch.

[gildor]

It waits because this is how Structured Concurrency and coroutine scope work

[marstran]

It because runBlocking creates a new CoroutineScope. A CoroutineScope will not complete before all child-coroutines complete. Look up "structured concurrency" 🙂

[gildor]

In general this code with runBlocking + launch doesn't look good

[gildor]

Because it doesn't use any coroutine features and just adds overhead on top of thread executor

[suppoze]

I tried with GlobalScope and it seems to be working as it should now 🙂 I'm pretty new to coroutine API and I might have been confusing dispatchers and coroutine scopes.
Thank you for clearing this up for me! I'll look up structured concurrency

In the end, I might leave the code as it was before because as you said @gildor it only adds overhead as of now 🙂

[gildor]

Coroutine make sense if you want to get result or your updateData method mostly waits, so you can use async API instead of blocking