I need some help with coroutines. I get that kotlin native only support coroutines on the main threa...

# kotlin-native

[Ola Gawell]

I need some help with coroutines. I get that kotlin native only support coroutines on the main thread. But it should be possible to execute a background task (for example a http request) without blocking the ui right? I tried to create a simple task that uses the Dispatchers.Main but then the ui is blocked. Here is my code:

[Ola Gawell]

Untitled

[Ola Gawell]

and the Android implementation...

[Ola Gawell]

Untitled

[alex009]

ktor-client by default executes http requests on background thread. not on ui. only result of request transfered into coroutine to execute other code of coroutine on ui thread

[alex009]

if you want just http requests - use ktor-client and all will be good

[alex009]

if you want do some expensive work - you can use https://github.com/Autodesk/coroutineworker
but you should pay attention to Kotlin/Native concurrency limitations. see https://github.com/Autodesk/coroutineworker#coroutineworker-prefers-frozen-state

[alex009]

also https://github.com/badoo/Reaktive also can change threads, but you have to write code for background tasks in the same way taking into account the limitations of Kotlin / Native

[alex009]

lambda & result also freeze just like in coroutineworker.

[Ola Gawell]

Thank you! Then I will stick to ktor until I need something else.

[Sam]

ktor-client uses URLSession on iOS which executes on a background thread and by default even delivers results on that background thread.

[Ola Gawell]

So if I execute a ktor request with

val result = client.get("url")

, do I need to do anything to get the result back on the ui thread?

[Sam]

No. Ktor takes care of that for you.

[Ola Gawell]

Do database calls with sqldelight work the same way? And how do I handle async read/write to local storage?

[Ola Gawell]

Like shared prefs

[Arkadii Ivanov]

Also Reaktive has thread local subscriptions and threadLocal() operator, both allow to avoid freezes in K/N in some circumstances.

[hooliooo]

@Sam Where’s the documentation in ktor that says it executes http requests on a background thread for iOS. I can’t seem to find it

[Sam]

Look under thread safety. https://developer.apple.com/documentation/foundation/urlsession

[hooliooo]

I’m aware in iOS, when the delegateQueue is set to nil, the framework automatically creates a serial background queue. I thought Ktor did something different, or at least did some configuration.