Still trying to wrap my head around how suspending functions

Question

Still trying to wrap my head around how suspending functions and coroutines come into play in a full complete production grade app non android

gildor · Answer

How Gradle or even Android related to this What is source of your confusion What exactly do you want to see There are many concepts in kotlinx coroutines channels actors mutexes lifecycle management etc Do you need particular examples or you just want to see how this works

asad.awadia · Answer

Because android mainly uses coroutines to switch work from main thread I m more interested in writing backend apps

asad.awadia · Answer

<https github com konrad kaminski spring kotlin coroutine tree master spring kotlin coroutine demo src main kotlin demo app> i basically want to see something like this but something that does real work and isn t spring or ktor

gildor · Answer

gt mainly uses coroutines to switch work from main thread Not only

gildor · Answer

I think you have too narrow requirements for your example It s obvious reasons why Ktor based on coroutines or Sprint most popular JVM framework for BE Probably you also can find some Vertex samples

gildor · Answer

all the examples are there maybe from different parts of kotlinx coroutines and from different types of project

gildor · Answer

kotlinx coroutines reached 1 0 only a month ago

gildor · Answer

if you have particular questions about implementation details or some patterns for backend development there is also < C0B8RC352|server> and this channel

gildor · Answer

It s just not very clear example of what you want to see just full sized app based on coroutines Someone will do this of course at some point but most adoptions now are not open sources maybe you could just write such sample yourself with help of community and Kotlin team

Dico · Answer

You should a video by Roman elizarov explaining coroutines there are a couple Preferably more recent ones

asad.awadia · Answer

< Dico> I have seen all of them they are all very scoped just to coroutines and have a lot of placeholder code

asad.awadia · Answer

I understand the coroutines part i m trying to understand how they fit into the entire app as a whole

asad.awadia · Answer

A lot of those slides just call delay that doesn t really help much

gildor · Answer

`delay` can be replaced with ANY async operation db request network request any other IO depending on you use case and your project

gildor · Answer

What do you expect to see there instead

asad.awadia · Answer

A blocking library call

asad.awadia · Answer

And or a suspend function wrapping a blocking call

asad.awadia · Answer

Also maybe explanation of what the thread is doing when the coroutine is suspended

asad.awadia · Answer

And also how everything ties into main

gildor · Answer

But this is very particular use case why do you need whole project for this

asad.awadia · Answer

As a template more than anything

asad.awadia · Answer

It s very easy to use coroutines incorrectly

gildor · Answer

I agree guide should contain examples and limitations of blocking call wrapping it was discussed some time ago but it s not a rocket since just wrap any blocking call with `withContext <http Dispatchers IO|Dispatchers IO> `

gildor · Answer

But you don t have cancellation support with this approach blocking call cannot be cancelled

gildor · Answer

gt As a template more than anything Template for what You can use coroutines with any project that have async libraries Ideally you shouldn t wrap blocking calls but use async API and coroutines adapter for this API

gildor · Answer

Also see this recent article by Roman <https medium com elizarov blocking threads suspending coroutines d33e11bf4761>

asad.awadia · Answer

Yes I read that as soon as it came out lol

gmariotti · Answer

< asad awadia> is not fully updated to Vert x 3 6 but it shows how coroutines can be used on a single thread

asad.awadia · Answer

Thanks I have seen most of these

SiebelsTim · Answer

Write a dispatcher and eventloop yourself Takes only a couple of lines and you get to see how it works in detail Especially logging when the dispatcher is invoked helped me to understand it

Felix · Answer

I ve some slides on the subject that eventually may help namely 1 On how `suspendCoroutine` works 2 An example using a Spring Controller <https speakerdeck com pmhsfelix using kotlin coroutines for asynchronous and concurrent>