Folks, I am writing my first coroutine. In the follow piece of code, I am fetching a bunch of objects and then doing a IO call with other service. Need some feedback whether my understanding of coroutine is correct.

val allWarehouses: List<Warehouse> = getWarehouses()

 GlobalScope.launch(<http://Dispatchers.IO|Dispatchers.IO>) {
        allWarehouses.forEach { warehouse ->
        	val notes = getNotes()
			// I want to run this loop in parallel
			notes.forEach {
			   serviceClient.markDone(note)  // this is an IO call 
			}
        }
}

I want to run the forEach operation in parallel. Is this the right way of doing?

Everything is within a single launch, so

markDone

will not run in parallel. This job however will be sent to an io thread relative to the contents outside of the launch. If you want to run all

markDone

in parallel, launch a separate task for each one.

separate task as in, put this another

launch {}

?

Yes. You should essentially have your launch inside the for loop

Wrap every operation to

async { }

using map: notes.map { async { markDone() } }.awaitAll()

thank you both 🙂 So, is the outer

launch(<http://Dispatchers.IO|Dispatchers.IO>)

in the right place?

It will throw exception when it fail and cancel other requests, but you can handle it, by replacing awaitAll() with map ++ await() and try/catch