http4k looks very interesting, I like how it focus...

# http4k

[janvladimirmostert]

http4k looks very interesting, I like how it focuses on just http instead of trying to do everything

few questions, when you do

val app = { request: Request ->

}
val server = app.asServer(Netty(9000)).start()

is the inside of that lambda a single thread or using some kind of event loop or is that server dependent?
when load testing (with Netty(9000)), I'm seeing nioEventLoopGroup-2-1 and nioEventLoopGroup-3-1..24, I'm assuming those 25 threads are from Netty?

how would one execute suspendable functions (or even blocking functions) inside that lambda?

val app = { request: Request ->
  	GlobalScope.launch {
		suspendableFunctionThatReturnsResponse()
	}
}
val server = app.asServer(Netty(9000)).start() // obviously doesn't compile since that app lambda doesn't return a Response

[s4nchez]

The lambda is just a plain Kotlin function. Its execution will depend on the context (i.e. backend where it runs).

[s4nchez]

We currently don't support coroutines. See this GitHub issue for the discussion around that topic.

[janvladimirmostert]

I saw that issue, just wondering if it can be retrofitted, something like this maybe

val app = { request: Request ->
			runBlocking {
				GlobalScope.async {
					delay(1000)
					Response(OK).body("DONE!!")
				}.await()
			}

[s4nchez]

In your example, app is an HttpHandler so it should work fine.

[s4nchez]

For making the actual HttpHandler suspendable, on the other hand, would cause all sort of issues with both clients and server backends, and we just haven't seen a good reason to do it yet.

[janvladimirmostert]

Once you start making things suspendable, it spreads and then everything all of a sudden needs to be suspendable
I like the simplicity of htt4k, if somebody wants to use CompletableFutures, this framework doesn't dictate that they have to use suspendable functions

I'm by no means an expert on Coroutines or Multithreading, would be nice to have a short section in the docs on what the recommended way is to work with either, maybe something for the backlog. Once I've gaine enough experience with Coroutines, I'd be happy to write such a section

[Razvan]

Not sure at this point it worth the hustle to move to coroutines. Project Loom will make it by default async so just wait for it will be easier... meanwhile I also sometimes miss the support especially when I want to run background tasks