SIGSEGV crash in ObjectMonitor::enter with latest Shenandoah JDK8

[Alexander Yakushev]

The object alignment part is most probably not the cause of this. The error
log I sent you is from a QA machine which is smaller, so I reduce -Xmx
there while keeping the rest of the options unchanged (including object
alignment). In production (where the crash originally happened), the heap
is set to 62g.

Regarding the fastdebug build, this will take a bit longer. Fastdebug build
is so slow that the application can't even start in time to not be killed
by the load balancer healthchecks:). I'll repat the experiment tomorrow.

On Mon, 4 Nov 2019 at 18:33, Aleksey Shipilev <shade at redhat.com> wrote:

> On 11/4/19 4:44 PM, Alexander Yakushev wrote:
> > Hello again! After some time, I finally managed to reproduce the crash
> in a non-production
> > environment with +ShenandoahVerify. I attach the hs_err file.
>
> Thanks. I notice that you are running in the unusual configuration:
>   -Xmx12g -Xms12g -XX:ObjectAlignmentInBytes=16
>
> Alignment to 16 bytes is not needed for the heap this small, and it just
> wastes memory.
>
> We are trying to see if that could be the source of bugs too...
>
> > This was reproduced with a regular shenandoah-jdk8 build. Meanwhile,
> I've built the application with
> > fastdebug build and will try with that too if necessary.
>
> Yes, that would be handy. The current hs_err does not yield interesting
> failure, it seems to be NULL
> dereference somewhere ObjectMonitor code -- which may or may not be the GC
> fault. Need to meditate
> on this a little bit...
>
> --
> Thanks,
> -Aleksey
>
>