Mutex is failing me on multithreaded coroutines with `InvalidMutabilityException: mutation attempt o...

# kotlin-native

[Hauke Radtki]

Mutex is failing me on multithreaded coroutines with InvalidMutabilityException: mutation attempt of frozen kotlinx.coroutines.sync.MutexImpl.LockedQueue when accessed from two different threads, even though the documentation states:

All core communication and synchronization objects in kotlin.coroutines such as Job, Deferred, Channel, BroadcastChannel, Mutex, and Semaphore are shareable. It means that they can be frozen for sharing with another thread and still continue to operate normally.

Anyone experienced this?

[Kris Wong]

confusingly, that same exception will be thrown when k/n expects something to be frozen and it's not

[Kris Wong]

if that's not the issue then it may be a bug

[Hauke Radtki]

True, and as far as I understand it's throwing this exception while setting the (optional) owner parameter, so that seems like a bug to me

[Hauke Radtki]

at kfun:kotlinx.coroutines.sync.MutexImpl.LockedQueue.<set-owner>#internal (0000000000589100)
        at kfun:kotlinx.coroutines.sync.MutexImpl.unlock(kotlin.Any?) (00000000005875a0)

[Hauke Radtki]

But also might be hiding another problem, or a missunderstanding how Kotlin/Native Mutexes should be used

[Hauke Radtki]

Filed it:
https://youtrack.jetbrains.com/issue/KT-38770