Hi. After upgrading Kotlin from 1.8.10 to 1.8.20, I observed a critical issue for `DebugProbes.jobTo...

# coroutines

[Vincent Péricart]

Hi. After upgrading Kotlin from 1.8.10 to 1.8.20, I observed a critical issue for DebugProbes.jobToString , blocking all threads of my coroutines executor:
• Threads are waiting for coroutineStateLock

at kotlinx.coroutines.debug.internal.DebugProbesImpl.hierarchyToString(DebugProbesImpl.kt:111)
	at kotlinx.coroutines.debug.DebugProbes.jobToString(DebugProbes.kt:98)

• In that particular thread dump, the thread holding the lock was doing

at kotlin.coroutines.CombinedContext.get(CoroutineContextImpl.kt:120)
	at kotlinx.coroutines.JobKt__JobKt.getJob(Job.kt:630)
	at kotlinx.coroutines.JobKt.getJob(Unknown Source)
	at kotlinx.coroutines.debug.internal.DebugProbesImpl.hierarchyToString(DebugProbesImpl.kt:115)
	at kotlinx.coroutines.debug.DebugProbes.jobToString(DebugProbes.kt:98)

Has anyone else encountered something similar?

[Dmitry Khalanskiy [JB]]

cc @Vsevolod Tolstopyatov [JB]

[Vsevolod Tolstopyatov [JB]]

The 1.7.0-Beta and 1.7.0-RC are no longer prone to this issue, the coroutine debugger was made lock-less (i.e. coroutineStateLock is gone).

Could you please tell if there is any progress in your application or if you are encountering a deadlock?

It's likely that hierarchyToString doesn't scale well with the number of coroutines and, while doing its string concatenation, was preventing your system from doing any progress.

If it is a deadlock though, it's a different issue that is worth investigating

[Vincent Péricart]

Thank you! It looked like there was no deadlock, just extremely slow performance.

I will try to apply 1.7.0-RC and get back to you if I still see the issue.