Trying to migrate to 1.3.0-rc-57 and 0.26.1-eap13 and I get errors for code that is basically: ``` s...

# coroutines

[spand]

Trying to migrate to 1.3.0-rc-57 and 0.26.1-eap13 and I get errors for code that is basically:

synchronized(lock){
    implicitScope.launch {
        delay(1)
    }
}

I get an error that says: " The 'delay' suspension point is inside a critical section". Seems safe to me ?

[Vsevolod Tolstopyatov [JB]]

But it’s not safe.
You have close to none guarantees on which thread coroutine will be resumed after delay.
And it’s impossible (at least on JVM) to acquire monitor on one thread and release it on another

[Vsevolod Tolstopyatov [JB]]

without this warning you’d likely to have IllegalMonitorException

[spand]

I dont expect the delay to take place on the initial thread.

[spand]

Or is there another problem ?

[Vsevolod Tolstopyatov [JB]]

I dont expect the delay to take place on the initial thread.

But synchronized machinery do, that’s why it is forbidden

[spand]

I am just a bit lost as to why this is allowed:

class Foo : CoroutineScope by GlobalScope {
    fun foo() = synchronized(Any()){
        myLaunch()
    }

    fun myLaunch(): Job = launch {
        delay(1)
    }
}

but after inlining myLaunch it is not. Why is it not just plain old normal blocking code?

[Vsevolod Tolstopyatov [JB]]

because myLaunch is not suspending function and does not suspend. It just launches new task with delay and this task will be executed outside of the syncrhonized block

[spand]

I am sorry if I am being daft, but why is that not the case in the inlined version ? launch is not a suspending function either. Why does the block given to launch have any relation to the synchronized here?

[spand]

Nothing, as far as I can see, makes the assumption to be run with the lock taken in the block given to launch, hence I cant see why it is a problem.

[uhe]

tbh that looks like a bug to me

[uhe]

I may decide to use normal synchronization to coordinate launching coroutines. The content of the actual launched coroutine should not matter.

[spand]

I dont get it either. It is up now as https://youtrack.jetbrains.com/issue/KT-27130

[Vsevolod Tolstopyatov [JB]]

oh, sorry, I’ve misunderstood you.
Thanks for the report!