Hi Need some help in understand some basic. I am h...

# coroutines

[Jgafner]

Hi
Need some help in understand some basic. I am holding a list of API requests I would like to execute in parallel.
I need to wait for all the responses, each response is a list and combine all of them into one list.

I still struggle to change the way I think with parallel Vs async - I ll be glad if someone can point me to a similar example in kotlin when async is used to fork and join a collection.
thanks

[vineethraj49]

i would assume,

makeManyRequests(list: List<R>) {
  list.map { r -> makeOneRequest(r) }.flatten()
}

// this is unbounded concurrency, do not do this ._.
suspend fun coMakeManyRequests(list: List<R>) = coroutineScope {
  list.map { r -> async { makeOneRequest(r) } }.awaitAll().flatten()
}

?

[Timo Gruen]

why not using the most simple way?

requestList
    .parallelStream()
    .map { request -> client.execute(request) }
    .toList()

[louiscad]

@Timo Gruen Because it's less efficient: blocks threads, meaning less parallelization, so slower execution.

[louiscad]

Also streams are JVM only

[Timo Gruen]

True, havn’t considered the blocking of the threads. Sure coroutines would be better I guess. Could you paste the corresponding example, how it would look like with Kotlin coroutines @louiscad?

[louiscad]

The snippet in this thread under "this is unbounded concurrency, do not do this ._." is actually correct so long as the list of request to do is not higher than the system can handle

[Jgafner]

thank you all