RFR: JDK-8132849: Increased stop time in cleanup phase because of single-threaded walk of thread stacks in NMethodSweeper::mark_active_nmethods()

[Roman Kennke]

Thanks Tobias for reviewing!

Erik: Is this good for you too?

Thanks,
Roman

> Hi Roman,
> 
> On 24.09.2018 18:46, Roman Kennke wrote:
>> http://cr.openjdk.java.net/~rkennke/JDK-8132849/webrev.05/
> 
> This looks good to me!
> 
> Best regards,
> Tobias
>