I just shifted my lauch3 just above coroutineS

Question

< Antanas A > I just shifted my lauch3 just above coroutineScope and it works just fine But surprisingly any thing below coroutineScope is never gonna execute It is blocking May be its a bug I have no idea

gildor · Answer

People could you please use threads it s hard to follow discussion of other messages

Antanas A. · Answer

yes of course coroutineScope call is blocking it is suspending your execution

Antanas A. · Answer

and blocks suspends until all children coroutines will be completed

Antanas A. · Answer

so in your example you are launching new coroutine inside coroutineScope and delaying 2seconds then 2seconds then MAX VALUE

Antanas A. · Answer

so that coroutine will never be completed

Antanas A. · Answer

so your coroutineScope also never completes because of parent child relationships

Antanas A. · Answer

so coroutineScope call will be blocked suspended and no execution would happen below that code

Antanas A. · Answer

it s not related to runBlocking or anything

Guru · Answer

It would have made sense if `runBlocking` would have had not returned to main as coroutineScope continue execution But it s blocking even a expression below that

Guru · Answer

isn t it a thread blocking

Antanas A. · Answer

could you explain what do you want to say

Antanas A. · Answer

you call coroutineScope will suspend execution until everything inside coroutineScope completes

Antanas A. · Answer

thats why you do not get anything executed after coroutineScope

Guru · Answer

yes you are correct but according to <http kotlinlang org> coroutineScope will not block the current thread while waiting for all children to complete

Antanas A. · Answer

no there are no any thread blocking

Antanas A. · Answer

could you give me an URL to exact doc

Antanas A. · Answer

maybe you ve misinterpreted something or there are bug in docs

Guru · Answer

Guru · Answer

go to Scope Builder section

Antanas A. · Answer

It creates new coroutine scope and does not complete until all launched children complete

Antanas A. · Answer

it says what I ve said

Antanas A. · Answer

but

Antanas A. · Answer

The main difference between runBlocking and coroutineScope is that the latter does not block the current thread while waiting for all children to complete Here I think where you ve got confused

Guru · Answer

yes

Guru · Answer

please correct me

tseisel · Answer

`coroutineScope` is NOT blocking It suspends as long as it has non completed children coroutines which is the case because it has a children coroutine launch2 that delays for a very very long time Note that `runBlocking` has nothing to do with that even without `runBlocking` launch3 would have to wait until children of `coroutineScope` have completed before resuming execution and reaching launch3

Antanas A. · Answer

to understand

Antanas A. · Answer

runBlocking is function and coroutineScope is suspend function if you ll call runBlocking anywhere inside code it will BLOCK current thread

Antanas A. · Answer

if you ll run coroutineScope it will SUSPEND execution

Antanas A. · Answer

but not a thread

Guru · Answer

ok thank you very much got it slightly smiling face

Antanas A. · Answer

the result feels the same but mechanics is different

Antanas A. · Answer

so I think you ve observed that execution has stuck

Antanas A. · Answer

And thought that thread has been blocked

Antanas A. · Answer

hope it helps you to understand

Guru · Answer

exactly yea thanks it is helpful to debug further

Guru · Answer

Thanks buddy All I did now is to put launch 1 launch 3 inside coroutineScoope and it is resuming its work now slightly smiling face

Antanas A. · Answer

actually you don t need that coroutineScope at all runBlocking itself will wait until all launches inside runBlocking will complete