RFR 8242484: Rework thread deletion during VM termination

[Robbin Ehn]

Hi Patricio, looks good, thanks.

/Robbin

On 2020-04-14 22:07, Patricio Chilano wrote:
> Hi,
> 
> Please review this small follow up for 8240918 to always delete the 
> JavaThread that calls Threads::destroy_vm().
> In 8240918 I added a conditional check in Threads::destroy_vm() to 
> prevent deleting a JavaThread when there are handshakers blocked in its 
> handshake_turn_sem semaphore.  We can actually avoid this issue 
> altogether if after removing the JavaThread from the active list and 
> before triggering the terminating safepoint, we wait until the 
> JavaThread is no longer protected by a ThreadsList reference.
> 
> Tested in mach5 tiers 1-6.
> 
> Bug:
>     https://bugs.openjdk.java.net/browse/JDK-8242484
> 
> Webrev:
>     http://cr.openjdk.java.net/~pchilanomate/8242484/v1/webrev/
> 
> Thanks,
> Patricio