Here if `unsafeMethod` fails it will make the parent job fai

Question

Here if `unsafeMethod` fails it will make the parent job fail which basically mean a crash of the UI componenent any working coroutine will be cancelled and further action would no longer work Of course I could encapsulate the call in `try catch` But it is a bit boilerplate and easy to forget here it is obvious but what about unexpected exceptions How could I launch a child coroutine in a way that it does nt propagate the failure to the parent

Pavel.AZ · Answer

using try catch inside your child coroutine for unsafe block

Jonathan · Answer

But what about unexpected exception Should I put try catch block everywhere for each function This is a lot of boilerplate code which is btw easy to forget

Pavel.AZ · Answer

Think you should log your unexpected exceptions using some UncaightException Handler and investigate it

Jonathan · Answer

Of course exception are logged using the default `UncaughtExceptionHandler`

Pavel.AZ · Answer

or try catch every block in development stage if you unsure

Jonathan · Answer

But I still want to make sure that the UI doesn t crash

Jonathan · Answer

even if an error has been logged and displayed to the user

Jonathan · Answer

gt or try catch every block in development stage if you unsure That s what I want to avoid And what about production It is even more true for production code I don t want the UI to crash in production either do I

Pavel.AZ · Answer

It s philosophical issue If you have some components that cannot be relied on your implementation i e NetworkRequests try catch it then user clicks on JButton it should not crash your app

Jonathan · Answer

Yes that s for expected exception I have no problem with that If a function is unsafe then it is encapsulated in a `try catch` and exception are managed

Jonathan · Answer

But I want my UI to be safe to all exceptions expected and unexpected ones expected ones are managed by `try catch` blocks and unexpected are logged and displayed to the user using an `UncaughtExceptionHandler` But still I d like that the UI remains usable even after unexpected exceptions

Jonathan · Answer

Here is a work around ``` abstract class ExceptionSafeCoroutineScope private val dispatcher CoroutineDispatcher CoroutineScope private var job = Job private val exceptionHandler = CoroutineExceptionHandler exception gt Thread getDefaultUncaughtExceptionHandler uncaughtException Thread currentThread exception job = Job final override val coroutineContext CoroutineContext get = job + dispatcher + exceptionHandler ``` But I wonder what is the recommended way of doing it

kevinherron · Answer

if you don t want the coroutine you launch to be a child of the current scope and everything that implies i e cancellation then maybe it s a candidate to be launched in another scope `GlobalScope launch `

Jonathan · Answer

Yes but I want it to be a child I still want all children to be cancelled at the end of life of the UI component

elizarov · Answer

I think I understand what you need We ve been thinking about this feature for a while Here I wrote it down <https github com Kotlin kotlinx coroutines issues 576>

Jonathan · Answer

Thank you < elizarov>