A question about `unsafeRunAsync`. I have a test w...

# arrow

[Mark Fisher]

A question about unsafeRunAsync. I have a test with 3 IO objects I've created and done an attempt() on, then I want them to run concurrently. I've tried using unsafeRunAsync expecting them to run ... asynchronously, but they run sequentially. How do I make the async IOs run concurrently?

@Test
    fun `io module test`() {
        val ioModule = Module(IO.async())
        ioModule.run {
            val ioS1 = repository.byId(u1).fix().attempt()
            val ioS2 = repository.byId(u2).fix().attempt()
            val ioS3 = repository.byId(u3).fix().attempt()
            <http://logger.info|logger.info> { "ioS1..." }
            ioS1.unsafeRunAsync { it.fold(ioError, ioInfo) }
            <http://logger.info|logger.info> { "ioS2..." }
            ioS2.unsafeRunAsync { it.fold(ioError, ioInfo) }
            <http://logger.info|logger.info> { "ioS3..." }
            ioS3.unsafeRunAsync { it.fold(ioError, ioInfo) }
        }
    }

My equivalent for using Observable was to use subscribeOn(...) as follows:

repository.byId(u1).fix().observable.subscribeOn(<http://Schedulers.io|Schedulers.io>()).subscribe(idLogger, errorLogger)
            repository.byId(u2).fix().observable.subscribeOn(Schedulers.computation()).subscribe(idLogger, errorLogger)
            repository.byId(u3).fix().observable.subscribeOn(Schedulers.newThread()).subscribe(idLogger, errorLogger)

How can I fix the io module test to run the 3 IO jobs at the same time?
Thanks!

[Mark Fisher]

Here's the version that worked for me in the end:

@Test
fun `io module test`() {
    val ioModule = Module(IO.async())
    ioModule.run {
        val ioS1 = repository.byId(u1).fix().attempt()
        val ioS2 = repository.byId(u2).fix().attempt()
        val ioS3 = repository.byId(u3).fix().attempt()

        val contextIO = IO.dispatchers().io()
        IO.parMapN(contextIO, ioS1, ioS2, ioS3) { a, b, c ->
            ioInfo(a)
            ioInfo(b)
            ioInfo(c)
        }.unsafeRunSync()
    }
}

[Mark Fisher]

where ioInfo is a helper function to print value of an Either:

private val ioInfo: (Either<Throwable, Int>) -> Unit = { result ->
    when (result) {
        is Either.Right -> <http://logger.info|logger.info> { "got stock: ${result.b}" }
        is Either.Left -> logger.error { "error: ${result.a}" }
    }
}