SIGSEGV crash in ObjectMonitor::enter with latest Shenandoah JDK8

[Roman Kennke]

Hi Alexander,

> Sorry, I didn't have a chance to continue the investigation. We've
> reverted to Shenandoah 1.0 since then and researched what it takes to
> move this particular service to JDK11 (which is a good idea anyway).

Hmm, ok. I'd sleep better if I could fix this bug. Or at least,
reproduce it. Or know if it's still present, even.

> I've noticed on Twitter that you managed to trigger a similar problem
> with Netty in the same method (ScheduleFutureTask.cancel). Did it lead
> anywhere?

No. This was an attempt to reproduce your problem. But I did not manage
to reproduce it so far.

I'll keep digging.

Thanks,
Roman